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HDAC Degrader

20230120211 · 2023-04-20

Assignee

Inventors

Cpc classification

International classification

Abstract

The disclosure provides compounds of formula (I). The compounds may be used to degrade the Histone Deacetylase (HDAC) family of enzymes, particularly HDAC.sub.1, 2 and .sub.3 that exist in corepressor complexes. Accordingly, the compounds may be used to treat cancer. The invention extends to pharmaceutical compositions comprising these compounds, and the use of these compounds in therapy.

##STR00001##

Claims

1. A compound of formula (I): ##STR00069## wherein L is a linker with a backbone comprising at least one group, the or each group being independently selected from the list consisting of an optionally substituted C.sub.1-C.sub.30 alkylene, an optionally substituted C.sub.2-C.sub.30 alkenylene, an optionally substituted C.sub.2-C.sub.30 alkynylene, NR.sup.3, O, S, SO, SO.sub.2, an optionally substituted C.sub.6-C.sub.12 arylene and an optionally substituted 5 to 10 membered heteroarylene, wherein the backbone of the linker is between 7 and 50 atoms in length; R.sup.1 is an E3 ligand; each R.sup.2 is independently a halogen, OR.sup.3, NR.sup.3R.sup.4, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl, C.sub.2-C.sub.6 alkynyl, a C.sub.6-C.sub.12 aryl group or a 5 to 10 membered heteroaryl group; R.sup.3 and R.sup.4 are independently H, C.sub.1-C.sub.6 alkyl, C.sub.2-C.sub.6 alkenyl or C.sub.2-C.sub.6 alkynyl; p is 0 or an integer between 1 and 4; or a pharmaceutically acceptable salt, solvate, tautomeric form or polymorphic form thereof.

2. The compound according to claim 1, wherein p is 0 or p is 1 and the compound of formula (I) is a compound of formula (Iaiii) or (Iaiv): ##STR00070##

3. (canceled)

4. The compound according to claim 1, wherein the E3 ligand is for the von Hippel-Lindau (VHL) E3 ubiquitin ligase, the cereblon E3 ubiquitin ligase, the cIAP1 E3 ubiquitin ligase or the MDM2 E3 ubiquitin ligase or a biologically active isoform or analogue thereof.

5. The compound according to claim 4, wherein R.sup.1 is: ##STR00071## ##STR00072## wherein X.sup.1 to X.sup.7 and X.sup.13 are each NH or O and R.sup.7 is H, an optionally substituted C.sub.1-C.sub.6 alkyl, an optionally substituted C.sub.2-C.sub.6 alkenyl, an optionally substituted C.sub.2-C.sub.6 alkynyl, an optionally substituted C.sub.3-C.sub.6 cycloalkyl, an optionally substituted 3 to 6 membered heterocycle, an optionally substituted phenyl or an optionally substituted 5 or 6 membered heteroaryl.

6. The compound according to claim 5, wherein R.sup.1 is ##STR00073## ##STR00074##

7. The compound of claim 6, wherein X.sup.1, X.sup.2 and X.sup.7 are NH and X.sup.3 and X.sup.13 are O and R.sup.7 is methyl or ##STR00075##

8. The compound according to claim 1, wherein the backbone of the linker is between 7 and 40, between 8 and 30, between 9 and 25, between 10 and 20 or between 11 and 15 atoms in length.

9. The compound according to claim 1, wherein L is -L.sub.1-L.sup.2-, wherein: L.sup.1 is absent or is -L.sup.3-L.sup.4-L.sup.5-L.sup.6- and L.sup.2 is -L.sup.7-L.sup.8-L.sup.9-L.sup.10-, wherein: L.sup.3 is an optionally substituted C.sub.1-C.sub.6 alkylene, an optionally substituted C.sub.2-C.sub.6 alkenylene or an optionally substituted C.sub.2-C.sub.6 alkynylene; L.sup.4 is NR.sup.5, O, S, ##STR00076## where an asterisk indicates a point of bonding to L.sup.5 or, if L.sup.5 is absent, L.sup.6; L.sup.5 is absent, an optionally substituted C.sub.1-C.sub.6 alkylene, an optionally substituted C.sub.2-C.sub.6 alkenylene or an optionally substituted C.sub.2-C.sub.6 alkynylene, an optionally substituted C.sub.6-C.sub.12 arylene or an optionally substituted 5 to 10 membered heteroarylene; L.sup.6 is an optionally substituted C.sub.6-C.sub.12 arylene or an optionally substituted 5 to 10 membered heteroarylene; L.sup.7 is absent, an optionally substituted C.sub.1-C.sub.6 alkylene, an optionally substituted C.sub.2-C.sub.6 alkenylene or an optionally substituted C.sub.2-C.sub.6 alkynylene; L.sup.8 is absent, ##STR00077## where an asterisk indicates a point of bonding to L.sup.9; L.sup.9 is an optionally substituted C.sub.1-C.sub.20 alkylene, an optionally substituted C.sub.2-C.sub.20 alkenylene or an optionally substituted C.sub.2-C.sub.20 alkynylene, wherein the backbone of the alkylene, alkenylene or alkynylene group is optionally interrupted by one or more heteroatoms selected from O or NR, or L.sup.9 is ##STR00078## where an asterisk indicates a point of bonding to L.sup.10 or, if L.sup.10 is absent, R.sup.1; L.sup.10 is absent, C(O) or ##STR00079## where an asterisk indicates a point of bonding to R.sup.1; L.sup.11 is independently absent, an optionally substituted C.sub.1-C.sub.5 alkylene, an optionally substituted C.sub.2-C.sub.5 alkenylene or an optionally substituted C.sub.2-C.sub.5 alkynylene; L.sup.12 and L.sup.13 are independently an optionally substituted C.sub.1-C.sub.5 alkylene, an optionally substituted C.sub.2-C.sub.5 alkenylene or an optionally substituted C.sub.2-C.sub.5 alkynylene; X.sup.8 to X.sup.12 are independently O or NR.sup.6; R.sup.5 and R.sup.6 are independently H, a C.sub.1-C.sub.6 alkyl, a C.sub.2-C.sub.6 alkenyl or a C.sub.2-C.sub.6 alkynyl; m is 0 an integer between 1 and 10; and n is an integer between 1 and 10.

10. The compound according to claim 9, wherein L.sup.1 is ##STR00080## where an asterisk indicates a point of bonding to L.sup.2.

11. The compound according to claim 9, wherein L.sup.1 is absent.

12. The compound according to claim 9, wherein L.sup.2 is ##STR00081## where an asterisk indicates a point of bonding to R.sup.1.

13. The compound according to claim 12, wherein L.sup.2 is ##STR00082## wherein: an asterisk indicates a point of bonding to R.sup.1; q is an integer of at least 5; r is an integer of at least 4; s is an integer of at least 2; t is an integer of at least 1; u is an integer of at least 3; v is an integer of at least 1; and w is an integer of at least 2.

14. The compound according to claim 1, wherein L is ##STR00083## wherein: an asterisk indicates a point of bonding to R.sup.1; q is an integer of at least 5; r is an integer of at least 4; s is an integer of at least 2; t is an integer of at least 1; u is an integer of at least 3; v is an integer of at least 1; and w is an integer of at least 2.

15. The compound according to claim 13, wherein: q is an integer between 5 and 20, between 7 and 15 or between 10 and 12; r is an integer between 4 and 20, between 7 and 15 or between 9 and 11; s is an integer between 2 and 10 or between 2 and 5; t is an integer between 1 and 10 or between 1 and 5; u is an integer between 2 and 15, between 3 and 12, between 4 and 10 or between 6 and 8; and w is an integer between 2 and 14, between 3 and 12, between 5 and 10 or between 7 and 9.

16. The compound according to any claim 13, wherein the compound of formula (I) is a compound of formula (Ic), (Id), (Ie) or (If): ##STR00084##

17. The compound of claim 16, wherein the compound is a compound of formula (Ic) and q is 11 or the compound is a compound of formula (Id) and r is 10.

18. The compound according to claim 1, wherein the compound is a compound of formula (101) to (116): ##STR00085## ##STR00086## ##STR00087## ##STR00088## ##STR00089##

19. A pharmaceutical composition for treating cancer in a subject, the composition comprising a compound of formula (I), as defined in claim 1, or a pharmaceutically acceptable complex, salt, solvate, tautomeric form or polymorphic form thereof and a pharmaceutically acceptable vehicle.

20. (canceled)

21. (canceled)

22. (canceled)

23. A method of treating, preventing or ameliorating cancer in a subject, the method comprising administering to a subject in need of such treatment, a therapeutically effective amount of the compound of formula (I), as defined by claim 1, or a pharmaceutically acceptable complex, salt, solvate, tautomeric form or polymorphic form thereof.

24. The method of claim 23, wherein the cancer is blood cancer, bowel cancer, brain cancer, breast cancer, cervical cancer, endometrial cancer, gastric cancer, liver cancer, lung cancer, ovarian cancer, pancreatic cancer, prostate cancer or skin cancer.

Description

[0092] FIG. 1 shows benzamide based HDAC inhibitors. CI-994 demonstrates selective inhibition for HDAC 1, 2 & 3, inhibits cell proliferation, induces apoptosis and has anti-tumor activity. MS-275 is a HDAC1 & 3 selective inhibitor with anti-tumor activity currently in phase III clinical trials for breast cancer. MGCD0103 is a HDAC 1, 2, 3 and 11 inhibitor in clinical trials for solid tumors and non-small cell lung cancer;

[0093] FIG. 2A is a schematic showing how when CI-994 is located in the binding pocket of HDAC2, the acetyl group of CI-994 is surface exposed from the HDAC2 catalytic active site (PDB: 4LY1); and FIGS. 2B and 2C show the structures of compounds synthesized by the inventors;

[0094] FIG. 3A is a graph showing AMC-Fluorescence Histone Deacetylase inhibition assay with the LSD1-CoREST-HDAC complex; and FIG. 3B shows Histone 3 Lysine 56 Acetylation (H3K56Ac) levels in E14 mouse embryonic stem cells after 24 h; CI-994=40 μM, Panobinostat=30 nM;

[0095] FIG. 4A shows an immunoblot with HDAC 1, 2 and 3 antibodies after 24 h treatment with the indicated reagents in HCT116 colon cancer cell line. Numerical value represents percentage with respect to DMSO control=100%; FIG. 4B shows Histone H3 Lysine 9 acetylation levels after 24 hours of the indicated treatments in HCT116 colon cancer cell line; and FIG. 4C shows NC-PROTAC4 with the inactive VHL diastereoisomer does not induce degradation in HCT116 cells. CI-994=40 μM, Panobinostat=30 nM;

[0096] FIG. 5 shows Fluorescence-Activated Cell Sorting (FACS) data of compound 4 and CI-994 in HCT116 colon cancer cell line;

[0097] FIG. 6 shows the structures of further compounds synthesized by the inventors;

[0098] FIG. 7 shows the effect of compound 2 on the levels of HDAC 1/2 in HCT116 cells following 24 h treatment; and

[0099] FIG. 8 shows the effects of other representative compounds on HDAC 1/2 in HCT116 cells following 24 h treatment.

EXAMPLE 1: SYNTHESIS OF FOUR PRELIMINARY PROTEOLYSIS TARGETING CHIMERAS (PROTACS)

[0100] For their PROTAC design, the inventors chose Benzamide based HDAC inhibitors that demonstrate selectivity for HDAC1, 2 and 3. CI-994 (see FIG. 1) has reported Ki values of 0.41 μM for HDAC1, 0.75 μM for HDAC3, and approximately 100 μM for HDAC8. This inhibitor exhibits phenotypes related to HDAC 1, 2 and 3, inhibiting cell proliferation, inducing apoptosis, and exhibiting broad antitumor activity in vitro and in vivo. CI-994 has been in clinical trials for its antitumor properties and analogous benzamides MS-275 and MGCD0103 (see FIG. 1) are currently in phase III clinical trials for breast cancer and non-small cell lung cancer. More recently CI-994 has also been reported for its neuroprotective effects in mice following spinal cord injury, the treatment of cognitive disorders, and reducing atrial fibrillation.

[0101] The inventors functionalized CI-994 from the acetyl group of the phenyl moiety (see PROTACs 1-4 shown in FIGS. 2B and C) as the acetyl group of an analogous benzamide inhibitor protrudes from the catalytic active site and is surface exposed in HDAC2 (see FIG. 2A). Accordingly, the inventors hypothesized that functionalization at this position may maintain HDAC binding. A short alkyl linker length was prepared (n=6) and a longer linker length prepared (n=12) as in previous PROTAC studies it has been shown the linker length can play an essential role in inducing degradation. Alkyl linkers were chosen to hasten synthesis. Two varying E3 ligands where also chosen; the von Hippel-Lindau (VHL) ligand, and the cereblon ligand, as the choice of E3 ligand, as well as linker length, can also influence successful protein-protein engagement with E3 ligase, and hence degradation.

EXAMPLE 2: EVALUATION OF PRELIMINARY PROTACS IN VITRO

[0102] The inventors evaluated their preliminary PROTACs in vitro using an established fluorescent deacetylase assay with the LSD1-CoREST-HDAC1 complex. This complex was used as an exemplary HDAC multiprotein complex to determine if such heterobifunctional molecules PROTACs 1-4 can still engage the HDAC enzyme in the context of an intact multiprotein complex. The IC.sub.50 values of PROTACs 1-4 were determined side by side with CI-994 as a positive control; as a negative control the inventors also synthesized Boc protected CI-994, compound 5 (see FIG. 3). Compound 5 is not capable of chelating zinc in the HDAC active site and should not demonstrate HDAC inhibition.

Discussion

[0103] The inventors observed that CI-994 had an IC.sub.50 value of approx. 0.5 μM consistent with the literature and 5 demonstrated no HDAC inhibition (see FIG. 3A). Preliminary PROTACs 1 and 3 with the shorter linker lengths all engaged HDAC1 in the CoREST complex with IC.sub.50 values directly comparable to CI-994, while the longer linker lengths, PROTACs 2 and 4, still maintained inhibition but had an approx. 10-15 fold inhibitory reduction compared to PROTACs 1 and 3.

EXAMPLE 3: EVALUATION OF PRELIMINARY PROTACS IN CELLS

[0104] The inventors proceeded to assess their compounds effects on HDAC activity in cells. In a previous study, the inventors demonstrated that acetylated histone H3 Lys56 (H3K56ac) is a direct substrate of HDAC1 in embryonic stem (ES) cells.

Discussion

[0105] To examine the ability of PROTACs 1-4 to reduce HDAC1, 2 and 3 activity in cells they began by measuring H3K56ac using quantitative western blotting (see FIG. 3B). CI-994 and the pan-HDAC inhibitor Panobinostat were used as positive controls. Acetylation levels of H3K56 where increased with Panobinostat and CI-994 as expected, intriguingly, only the PROTACs with longer linker lengths, i.e. PROTACs 2 and 4, caused an increase in acetylation to similar levels (see FIG. 3B).

[0106] The inventors speculate that PROTACs 1 and 3 although active in vitro, may be unable to reach their cellular target for HDAC inhibition or degradation.

[0107] With conformation that PROTACs 2 and 4 decrease Histone Deacetylation activity in vitro and in cells, the inventors proceeded to quantify HDAC1, 2 and 3 protein abundance. In ES cells partial degradation was observed (data not shown) however degradation was even more prominent in human colon cancer cell line HCT116. After 24 hours degradation was observed in a dose dependent manner (see FIG. 4A). The VHL based PROTAC 4 was a more effective degrader than the Cereblon PROTAC 2, see FIG. 7. HDAC1 and 2 underwent near complete degradation at 10 μM with PROTAC 4, while HDAC3 levels were also decreased. At 1 μM approximately 50% degradation was observed for HDAC 1, 2 and 3. Intriguingly, even at a 10 nM of PROTAC 4 complete HDAC 1 and 2 levels were not recovered.

[0108] Acetylation levels of Histone H3 Lys9 (H3K9ac), another established residue for HDAC activity, were also determined in HCT116 cells after 24 hours treatment with PROTAC 4. At 10 μM of PROTAC 4 acetylation levels were highly elevated compared to the DMSO control (FIG. 4B), consistent with a reduction in HDAC1 and 2 levels at 10 μM (FIG. 4A). However, at 1 μM with HDAC1, 2 & 3 at approximately 40-48% levels H3K9 acetylation levels were similar to the DMSO control. Indicating for significantly increased acetylation, in H3K9ac at least, near complete HDAC degradation is required and partial degradation is not sufficient. To confirm HDAC degradation was occurring via a VHL mediated proteasome degradation pathway the inventors synthesised NC-PROTAC4 with the inactive diastereoisomer of VHL (FIG. 4C). No degradation of HDAC 1 & 2 was observed when compared side by side with PROTAC 4 confirming degradation is occurring via a VHL mediated E3 ligase pathway.

EXAMPLE 4: EVALUATION OF THE EFFECTS OF PROTAC 4 ON THE CELL CYCLE IN THE COLON CANCER HCT116 CELL LINE USING FLUORESCENCE-ACTIVATED CELL SORTING (FACS)

[0109] The inventors then investigated the effect of PROTAC 4 on the cell cycle in the colon cancer HCT116 cell line.

[0110] After 48 hours significant cell death was observed at 10 μM of PROTAC 4 (FIG. 5). At 40 μM cell death after 48 hours was at similar levels to CI-994. Although the effect of PROTAC 4 on cell viability was comparable to CI-994 it's important to note the IC.sub.50 of PROTAC 4 against the LSD1-CoREST-HDAC1 complex in vitro is 16.8 μM, compared to 0.5 μM for CI-994, with near complete HDAC1 and 2 degradation being observed with PROTAC 4 at 10 μM. Hence, the observed phenotype with PROTAC 4 is most likely due to degradation, rather than inhibition, of the CoREST complex and other HDAC1 & 2 containing complexes in the cell.

EXAMPLE 5: SYNTHESIS OF FURTHER PROTACS

[0111] The inventors further synthesized PROTACs 5-10 (see FIGS. 2B, 2C 6A, and 6B).

EXAMPLE 6: SYNTHESIS AND EVALUATION OF STILL FURTHER PROTACS

[0112] The inventors further synthesized the following PROTACs.

##STR00031## ##STR00032## ##STR00033## ##STR00034##

[0113] The compounds were screened at 0.1 μM, 1 μM and 10 μM in a HCT116 cell line. The maximum degradation observed irrespective of the concertation was recorded. The screening of the new compounds was done in 6-well plates, 5 mL media, with 400,000 cells per well to increase throughput. FIG. 8 shows representative compounds.

[0114] The activity of the compounds was analyzed and compared to PROTAC4 and the results are provided in the table below. CI-994 and BocCI-994 are provided as positive and negative controls, respectively, for CoREST, NuRD, MiDAC and SMRT assays.

[0115] It will be noted that the IC.sub.50 value for PROTAC4 differs from the one in FIG. 3 due to the assay having been run under different conditions.

TABLE-US-00001 TABLE 1 Biological activity of PROTACs CoREST NuRD MiDAC SMRT HDAC1 Compound IC.sub.50 IC.sub.50 IC.sub.50 IC.sub.50 Degrader Name (μM) (μM) (μM) (μM) (% Degradation) CI-994 1.79 1.37 9.69 0.423 N/A BocCI-994 ND ND ND N/A PROTAC4 0.394 0.418 0.336 0.414 85% PROTAC6 0.244 0.338 1.69 60% PROTAC7 3.7 3.24 17.23 28% PROTAC12 7.17 8.13 5.15 42% PROTAC13 0.845 1.18 1.43 0.345 58% PROTAC14 0.993 1.15 1.39 0.406 34% PROTAC16 4.13 11.8 67% PROTAC22 32% PROTAC17 3.81 0.86 58% PROTAC20 51% PROTAC26 88% PROTAC28 No PROTAC29 39% PROTAC34 47% PROTAC35 61% PROTAC36 51% PROTAC37 38% HDAC 2 HDAC 3 Increase Compound Degrader degrader H3K56Ac Name (% Degradation) (% Degradation) (Y/N/partial) CI-994 N/A N/A Y BocCI-994 N/A N/A PROTAC4 76% 63% Y PROTAC6 partial not tested Y PROTAC7 No 43% Y PROTAC12 46% 32% Y PROTAC13 52% 69% Y PROTAC14 39% 83% Y PROTAC16 58% 67% Y PROTAC22 No 32% Y PROTAC17 21% 46% partial PROTAC20 26% 67% partial PROTAC26 58% 88% Y PROTAC28 No 57% partial PROTAC29 23% 64% PROTAC34 44% 30% PROTAC35 49% 38% PROTAC36 28% 69% PROTAC37 16% 37%

Discussion

[0116] The inventors have synthesized a number of compounds with IC.sub.50 values comparable to CI-994 in the CoREST, NuRD, MiDAC and SMRT complexes. Furthermore, when tested in cells, the compounds were also found to be HDAC degraders.

[0117] Without wishing to be bound by theory, the inventors note that where low degradation is observed, it could indicate that a PROTAC targets a specific complex. For instance, the thiophene group in the head group of PROTAC22 is thought to make the PROTAC selective for CoREST. Accordingly, the relatively low % HDAC degradation which is observed for this compound could be due to this selectivity.

Conclusions

[0118] The PROTAC approach has been applied to a number of protein targets, yet, importantly, not all proteins are as amenable to degradation. This has been observed with PROTACs based on non-selective pan-kinase inhibitors. Non-complex forming, cytoplasmic localized HDAC6 has also recently been identified as a preferential target for degradation with hydroxamic acid based PROTACs. The inventors have identified degraders of nucleus localized HDAC 1, 2 and 3, components of multiprotein corepressor complexes. Near complete HDAC 1, 2 & 3 degradation is required to significantly influence acetylation levels of certain HDAC markers in cells. However, it can be envisaged that with potential complex selective degraders global acetylation levels, and certain HDAC acetylation markers, may not be as increased in comparison to pan-HDAC inhibitors, yet may exhibit greater efficacy or reduced side effects to a HDAC corepressor complex related to a specific disease. Unexpectedly, the inventors found that the length of the alkyl linker was critical for cell permeability. Compounds 1 and 3 despite being a lower molecular weight and better HDAC inhibitors in vitro than 2 and 4, failed to alter histone acetylation levels in cells. It seems likely that the length and chemical nature of PROTAC linkers will have a profound effect on their activity in cells. HDAC degraders, such as those identified above, may offer an alternative strategy to important HDAC corepressor complex chemical probes and therapeutics.

Materials and Methods

General Methods

[0119] Starting materials and solvents used were purchased from commercially available sources and used without further purification. Dried THF and DCM were dried using an Innovative Technology inc. PureSolv solvent purification system. All chemical names have been generated using ChemDraw Professional. Unless otherwise stated, all reactions were stirred and carried out under nitrogen. All reactions were observed using TLC which was run on aluminium-backed silica. Preparative column chromatography and flash column chromatography using a Biotage Isolera purification system was performed using silica gel 60 (230-400 mesh).

[0120] Analytical and semi-preparative HPLC were performed on a ThermoFisher Ultimate 3000 system with Chromeleon software on a Phenomenex Luna C18 column. Method 1, A=H.sub.2O, B=CH.sub.3CN, 5-100% B, 10 mL/min flow, 45 min gradient. Method 2, A=0.1% TFA in H.sub.2O, B=0.1% TFA in CH.sub.3CN, 5-100% B, 10 mL/min flow, 45 min gradient.

[0121] Nuclear magnetic resonance (NMR) spectra were acquired using a Bruker 500 (.sup.1H, 500 MHz; .sup.13C 125 MHz) or Bruker 400 (.sup.1H, 400 MHz; .sup.13C 100 MHz) instrument at ambient temperature using deuterated solvent as reference—CDCl.sub.3 (δ.sub.H=7.26 ppm, δ.sub.C=77.00 ppm), DMSO-d.sub.6 (δ.sub.H=2.50 ppm, δ.sub.C=39.51 ppm), CD.sub.3OD (δ.sub.H=3.31 ppm, δ.sub.C=49.15 ppm), or CD.sub.3CN (SH=1.94 ppm, (c=1.39, 118.69 ppm). ACDLabs software (Chemsketch and Spectrus Processor) was used for peak picking, integration and calculating coupling constants. High resolution mass spectra (HRMS) were recorded on a Water Aquity XEVO Q ToF machine and measured in m/z. The structures of all products were confirmed by analysis of the .sup.1H NMR spectra and mass spectra.

[0122] General Method A. DIPEA (1.5 equiv.) was added to a solution of substituted aniline (1 equiv.) in dry DCM (2.5 mL/mmol) at 0° C., followed by the dropwise addition of 4-nitrobenzoyl chloride (1.1 equiv.) as a solution in dry DCM. The mixture was stirred at 0° C. for 30 minutes, then at room temperature overnight. The reaction mixture was diluted with DCM and then washed with sat. NaHCO.sub.4, 1M HCl and sat. NaCl. The organic layer was then dried over Na.sub.2SO.sub.4, concentrated in vacuo, then purified accordingly to afford the desired compound.

[0123] General Method B. Triethylamine (3 equiv.) was added to a solution of 4-aminobenzamide starting material (1 equiv.) in dry THF (10 mL/mmol) at 0° C., followed by the dropwise addition of acetyl chloride (1.2 equiv.). The mixture was stirred at 0° C. for 30 minutes, then at room temperature for 2 hours. The reaction mixture was concentrated in vacuo to give the corresponding crude, which was chromatographically purified to afford the desired compound.

[0124] General Method C. TFA (20 equiv.) was added to a stirring solution of Boc-protected HDAC inhibitor/inhibitor-linker (1 equiv.) in DCM (10 mL/mmol) and the resulting reaction mixture stirred at room temperature for 6 hours. The reaction mixture was concentrated in vacuo, dissolved in MeOH (0.1 M), agitated in MP-carbonate resin (3.02 mmol/g loading capacity) for 2-3 hours and then filtered. The filtrate was concentrated in vacuo to afford the desired HDAC inhibitor/inhibitor-linker.

[0125] General Method D. To a solution of dicarboxylic acid (1 equiv.) in 1,4-dioxane/DMF (1:1, 4 mL/mmol), was added benzyl bromide (1 equiv.), followed by the addition of NaHCO.sub.3 (1 equiv.). The resulting suspension was heated at 90° C. overnight. The reaction mixture was left to cool to room temperature and then concentrated in vacuo. The crude residue was then suspended in EtOAc and washed with sat. NaCl and water. The organic phase was dried over MgSO.sub.4, filtered and concentrated in vacuo to afford the corresponding crude, which was chromatographically purified to afford the desired compound.

[0126] General Method E. To a solution of acid linker (1.1-1.3 equiv) in dry DMF (10 mL/mmol) at 0° C., DIPEA (3 equiv.) and HATU (1.3-1.5 equiv.) were added. The reaction mixture was stirred for 15 minutes, after which a solution of amine (1 equiv.) in DMF was added slowly and the resultant solution stirred at room temperature overnight. The reaction mixture was diluted in EtOAc, then washed with sat. NaHCO.sub.3 and sat. NaCl. The organic layer was dried over MgSO.sub.4, filtered and concentrated in vacuo to give the corresponding crude, which was chromatographically purified to afford the desired compound.

[0127] General Method F. To a solution of the benzyl ester protected HDACi-linker conjugate (1 equiv.) in THF, 10% Pd/C (10% wt) was added. The reaction flask was filled with nitrogen and evacuated 3 times using a Shlenk line, before a balloon of hydrogen was added and the resultant mixture stirred vigorously for 4-18 hours. The balloon of hydrogen was removed and the flask was flushed with nitrogen The reaction mixture was filtered through a glass microfiber filter paper, and the filtrate concentrated in vacuo to afford the desired compound.

[0128] General Method G. To a solution of HDACi-linker acid (1.2 equiv.) in dry DMF (1 mL) at 0° C., DIPEA (3 equiv.) and HATU (1.3 equiv.) were added. The reaction mixture was stirred for 15 minutes, after which a solution of (4R)-3-Methyl-L-valyl-4-hydroxy-N-[[4-(4-methyl-5-thiazolyl)phenyl]methyl]-L-prolinamide hydrochloride (VH_032 amine, 0.08-0.10 mmol) in DMF (1 mL) was added slowly and the resultant solution stirred at room temperature for 16 hours. The reaction mixture was diluted in EtOAc (10 mL), then washed with sat. NaHCO.sub.3 (2×5 mL) and sat. NaCl (2×5 mL). The organic layer was dried over MgSO.sub.4, filtered, and concentrated in vacuo to give the corresponding crude, which was chromatographically purified to afford the desired compound.

[0129] General Method H. TFA (0.4 mL or 20 equiv.) was added to a stirring solution of Boc-protected PROTAC (1 equiv.) in DCM (2 mL) and the resulting reaction mixture stirred at room temperature for 4-6 hours. The reaction mixture was concentrated in vacuo, dissolved in MeOH (2 mL), agitated in MP-carbonate resin (3.02 mmol/g loading capacity) for 2-3 hours and then filtered. The filtrate was concentrated in vacuo and the resulting solid dissolved in MeCN:H.sub.2O (1:1) and lyophilised to remove residual TFA impurities, affording the final PROTAC.

[0130] General Method I. A mixture of E3 ligand phenol (1 equiv.), alkyl bromide (1 equiv.) and K.sub.2CO.sub.3 (3 equiv.) in dry DMF (0.8 mL) was stirred at 70° C. overnight. The reaction was concentrated in vacuo to give the corresponding crude, which was chromatographically purified to afford the desired compound.

[0131] General Method J. To a solution of 2-((2-(2,6-dioxopiperidin-3-yl)-1,3-dioxoisoindolin-4-yl)oxy)acetic acid (CRBN acid, 1 equiv.) in dry DMF (2 mL) at 0° C., DIPEA (3 equiv.) and HATU (1.2 equiv.) were added. The reaction mixture was stirred for 15 minutes, after which a solution of HDACi-linker amine (1 equiv.) in DMF (1 mL) was added slowly and the resultant solution stirred at room temperature for 18 hours. The reaction mixture was diluted in EtOAc (10 mL), then washed with sat. NaHCO.sub.3 (2×10 mL) and sat. NaCl (2×10 mL). The organic layer was dried over MgSO.sub.4, filtered and concentrated in vacuo to give the corresponding crude, which was chromatographically purified to afford the final PROTAC.

[0132] General Method K. To a solution of HDACi-linker acid (1.2 equiv.) in dry DMF (1 mL) at 0° C., DIPEA (3 equiv.) and HATU (1.3 equiv.) were added. The reaction mixture was stirred for 15 minutes, after which a solution of tert-butyl ((S)-1-(((S)-2-((2S,4S)-4-amino-2-(((R)-1,2,3,4-tetrahydronaphthalen-1-yl)carbamoyl)pyrrolidin-1-yl)-1-cyclohexyl-2-oxoethyl)amino)-1-oxopropan-2-yl)(methyl)carbamate hydrochloride (A 410099.1 amine, 0.04 mmol) in DMF (1 mL) was added slowly and the resultant solution stirred at room temperature for 16 hours. The reaction mixture was diluted in EtOAc (10 mL), then washed with sat. NaHCO.sub.3 (2×5 mL) and sat. NaCl (2×5 mL). The organic layer was dried over MgSO.sub.4, filtered, and concentrated in vacuo to give the corresponding crude, which was chromatographically purified to afford the desired compound.

Synthesis of HDAC Inhibitor (HDACi)

[0133] ##STR00035## ##STR00036## ##STR00037## ##STR00038##

[0134] Tert-butyl (2-aminophenyl)carbamate (2): A solution of Boc.sub.2O (6.05 g, 27.7 mmol) in THF (50 mL) was added dropwise over 3 hours to a solution of 7 (3.00 g, 27.7 mmol) and triethylamine (4.64 mL, 33.3 mmol) in THF (25 mL) at 0° C., then the mixture was stirred at room temperature for 15 hours. The reaction was mixture concentrated in vacuo to afford a grey crystalline solid and then re-dissolved in EtOAc (50 mL). This solution was washed with water (2×30 mL) and sat. brine (2×30 mL), filtered over Na.sub.2SO.sub.4, then concentrated in vacuo to afford a yellow/grey solid. The crude solid was purified by column chromatography (solid load, 10-25% EtOAc in hexane) to afford 8 (4.72 g, 22.5 mmol, 82% yield) as a yellow/grey solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.11H.sub.16N.sub.2O.sub.2Na: 231.1109, found 231.1112.

[0135] Tert-butyl (5-fluoro-2-nitrophenyl)carbamate (4): A solution of 2 (4.61 g, 19.2 mmol) in THF (5 mL) was added dropwise to a solution of 3 (300 g, 19.2 mmol), DMAP (59 mg, 0.48 mmol) and triethylamine (154 mL, 11.06 mmol) in THF (5 mL) at 0° C., and then the mixture was stirred at 80° C. for 15 hours. The reaction mixture was concentrated in vacuo, then redissolved in EtOAc (10 mL) and 2M HCl (100 mL) added. The EtOAc layer was collected and then the aqueous layer extracted with further EtOAc (2×100 mL). The combined organic layers were dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo to afford an orange oil (5.10 g). The crude product was purified by column chromatography (10-20% EtOAc in hexane) to afford 4 (2.77 g, 10.7 mmol, 56% yield) as a yellow crystalline solid. HRMS (ESI, direct infusion) m/z: [M−H].sup.− calculated for C.sub.11H.sub.12N.sub.2O.sub.4F: 255.0781, found 255.0780.

[0136] Tert-butyl (2-amino-5-fluorophenyl)carbamate (5): To a solution of 4 (1.68 g, 6.56 mmol) in MeOH (50 mL), 10% Pd/C (170 mg) was added. The reaction flask was filled with nitrogen and evacuated 3 times using a Shlenk line, before a balloon of hydrogen was added and the resultant mixture stirred vigorously for 4.5 hours. The balloon of hydrogen was removed and the flask was flushed with nitrogen. The reaction mixture was filtered through a glass microfiber filter and then the filtrate was concentrated in vacuo to afford 5 (1.43 g, 6.26 mmol, 96% yield) as a beige solid. MS (ESI) m/z: 227 [M+H].sup.+.

[0137] Tert-butyl (4-bromo-2-nitrophenyl)carbamate (7): A solution of Boc.sub.2O (2.21 g, −1014 mmol) in THF (5 mL) was added dropwise to a solution of 6 (2.00 g, 9.22 mmol), DMAP (0.113 g, 0.92 mmol) and triethylamine (1.54 mL, 11.06 mmol) in THF (35 mL) at 0° C., and then the mixture was stirred at 60° C. for 16 hours. The reaction mixture was concentrated in vacuo and then purified by column chromatography (0-50% EtOAc in hexane) to afford 7 (1.524 g, 4.76 mmol, 47% yield) as a yellow crystalline solid. HRMS (ESI) m/z: [(M-Boc)+H].sup.+ calculated for C.sub.6H.sub.6BrN.sub.2O.sub.4 (.sup.81Br): 218.9592, found 218.9594.

[0138] Tert-butyl (2-nitro-4-(thiophen-2-yl)phenyl)carbamate (8): To a solution of DME/water (2:1, 36 mL) was added thiophen-2-ylboronic acid (0.77 g, 6.05 mmol), 7 (1.60 g, 5.05 mmol), Na.sub.2CO.sub.3 (0.80 g, 7.57 mmol) and Pd(PPh.sub.3).sub.4 (0.38 g, 0.33 mmol). The resulted mixture was stirred vigorously at 110° C. for 16 hours. The reaction mixture was diluted with more water (40 mL) and then the product was extracted with EtOAc (3×50 mL). The organic layers were combined, washed with water (2×70 mL), dried over MgSO.sub.4, filtered and concentrated in vacuo to afford a brown solid (1.920 g). The crude product was purified by column chromatography (dry load, 0-50% EtOAc in hexane) to give 8 (1.21 g, 3.74 mmol, 74% yield) as an orange crystalline solid. HRMS (ESI) m/z: [M−H].sup.− calculated for C.sub.15H.sub.15N.sub.2O.sub.4S: 319.0753, found 319.0753.

[0139] Tert-butyl (2-amino-4-(thiophen-2-yl)phenyl)carbamate (9): To a solution of 8 (1.181 g, 3.69 mmol) in MeOH (15 mL), 10% Pd/C (0.120 g) was added. The reaction flask was filled with nitrogen and evacuated 3 times using a Shlenk line, before a balloon of hydrogen was added and the resultant mixture stirred vigorously for 4 hours. The balloon of hydrogen was removed and the flask was flushed with nitrogen. The reaction mixture was filtered through a glass microfiber filter and then the filtrate was concentrated in vacuo to afford 9 (1.057 g, 3.60 mmol, 98% yield) as a brown solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.15H.sub.19N.sub.2O.sub.2S: 291.1167, found 291.1167.

[0140] Tert-butyl (2-(4-nitrobenzamido)phenyl)carbamate (10a): Following general method A, 10a was obtained from 2 (4.17 g, 20.0 mmol) and 4-nitrobenzoyl chloride (4.09 g, 22.0 mmol). The crude product was triturated in EtOH and then filtered to afford 10a (5.52 g, 15.3 mmol, 76% yield) as a pale yellow solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.18H.sub.19N.sub.3O.sub.5Na: 380.1222, found 380.1223.

[0141] Tert-butyl (5-fluoro-2-(4-nitrobenzamido)phenyl)carbamate (10b): Following general method A, 10b was obtained from 5 (1.27 g, 5.60 mmol) and 4-nitrobenzoyl chloride (1.15 g, 6.17 mmol). The crude product was purified by column chromatography (0-50% EtOAc in hexane) to afford 10b (1.87 g, 4.93 mmol, 88% yield) as a fluffy, pale brown solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.18H.sub.18N.sub.3O.sub.5FNa: 398.1128, found 398.1125.

[0142] Tert-butyl (2-(4-nitrobenzamido)-4-(thiophen-2-yl)phenyl)carbamate (10c): Following general method A, 10c was obtained from 9 (400 mg, 1.38 mmol) and 4-nitrobenzoyl chloride (284 mg, 1.53 mmol). The crude product was triturated in EtOH and then filtered to afford 10c (459 mg, 1.04 mmol, 76% yield) as a pale green solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.22H.sub.22N.sub.3O.sub.5S: 440.1280, found 440.1280.

[0143] Tert-butyl (2-(4-aminobenzamido)phenyl)carbamate (11a): To a solution of 10a (5.52 g, 15.3 mmol) in MeOH/THF (1:1, 100 mL), 10% Pd/C (0.55 g) was added. The reaction flask was filled with nitrogen and evacuated 3 times using a Shlenk line, before a balloon of hydrogen was added and the resultant mixture stirred vigorously for 18 hours. The balloon of hydrogen was removed and the flask was flushed with nitrogen. The reaction mixture was filtered through celite, then the celite was washed with more MeOH (3×50 mL) and the filtrate concentrated in vacuo to afford 11a (5.23 g, 15.3 mmol, 100% yield) as a fluffy white crystalline solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.18H.sub.21N.sub.3O.sub.3Na: 350.1481, found 350.1486.

[0144] Tert-butyl (2-(4-aminobenzamido)-5-fluorophenyl)carbamate (11b): To a solution of 10b (1.525 g, 4.063 mmol) in MeOH (100 mL), 10% Pd/C (0.155 g) was added. The reaction flask was filled with nitrogen and evacuated 3 times using a Shlenk line, before a balloon of hydrogen was added and the resultant mixture stirred vigorously for 7 hours. The balloon of hydrogen was removed and the flask was flushed with nitrogen. The reaction mixture was filtered through a glass microfiber filter and then the filtrate was concentrated in vacuo to afford 11b (1.335 g, 3.827 mmol, 94% yield) as a pale grey crystalline solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.18H.sub.21N.sub.3O.sub.3F: 346.1567, found 346.1563.

[0145] Tert-butyl (2-(4-aminobenzamido)-4-(thiophen-2-yl)phenyl)carbamate (11c): To a solution of 10c (0.333 g, 0.76 mmol) in MeOH/DCM (1:1, 120 mL), SnCl.sub.2 (0.863 g, 4.55 mmol) was added and the resultant mixture stirred at room temperature for 1 week. The reaction mixture was cooled to 0° C., then saturated Na.sub.2CO.sub.3 (40 mL) was added slowly. The product was extracted into DCM (4×40 mL), then the organic layers were combined and washed with brine (2×80 mL). The organic layer was dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo to afford 11c (0.283 g, 0.62 mmol, 82% yield) as a yellow crystalline solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.22H.sub.24N.sub.3O.sub.3S: 410.1538, found 410.1530.

[0146] Tert-butyl (2-(4-acetamidobenzamido)phenyl)carbamate (12a): Following general method B, 12a was obtained from 11a (200 mg, 0.611 mmol) and acetyl chloride (0.052 mL, 0.733 mmol). The crude product was purified by column chromatography (dry load, 100% EtOAc) to afford 12a (193 mg, 0.517 mmol, 85% yield) as a white solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.20H.sub.23N.sub.3O.sub.4Na: 392.1586, found 392.1586.

[0147] Tert-butyl (2-(4-acetamidobenzamido)-5-fluorophenyl)carbamate (12b): Following general method B, 12b was obtained from 11b (95.7 mg, 0.277 mmol) and acetyl chloride (0.024 mL, 0.333 mmol). The crude product was purified by column chromatography (dry load, 50-100% EtOAc) to afford 12b (101.0 mg, 0.258 mmol, 93% yield) as a pale yellow/brown solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.20H.sub.23FN.sub.3O.sub.4: 388.1673, found 388.1672.

[0148] Tert-butyl (2-(4-acetamidobenzamido)-4-(thiophen-2-yl)phenyl)carbamate (12c): Following general method B, 12c was obtained from 11c (96.6 mg, 0.236 mmol) and acetyl chloride (0.020 mL, 0.283 mmol). The crude product was purified by column chromatography (0-100% EtOAc) to afford 12c (72.8 mg, 0.160 mmol, 68% yield) as a pale yellow/green solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.24H.sub.26N.sub.3O.sub.4S: 452.1644, found 452.1643.

[0149] 4-acetamido-N-(2-aminophenyl)benzamide (CI-994): Following general method C, Boc deprotection of 12a (47.5 mg, 0.129 mmol) was performed to afford CI-994 (35.6 mg, 0.126 mmol, 97% yield) as a yellow/white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.15H.sub.16N.sub.3O.sub.2: 270.1243, found 270.1247.

[0150] 4-acetamido-N-(2-amino-4-fluorophenyl)benzamide (BRD3308): Following general method C, Boc deprotection of 12b (87.0 mg, 0.225 mmol) was performed to afford BRD3308 (59.3 mg, 0.202 mmol, 90% yield) as a yellow/brown solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.15H.sub.15FN.sub.3O.sub.2: 288.1148, found 288.1139.

[0151] 4-acetamido-N-(2-amino-5-(thiophen-2-yl)phenyl)benzamide (Cpd-60): Following general method C, Boc deprotection of 12c (48.2 mg, 0.107 mmol) was performed to afford Cpd-60 (35.5 mg, 0.100 mmol, 93% yield) as a pale yellow/green solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.19H.sub.18N.sub.3O.sub.2S: 352.1120, found 352.1120.

Synthesis of Linker

[0152] ##STR00039##

[0153] 9-(benzyloxy)-9-oxononanoic acid (14a): Following general method D, 14a was obtained from 13a (2.00 g, 10.63 mmol) and benzyl bromide (1.26 mL, 10.63 mmol). The crude product was purified by column chromatography (50% EtOAc in hexane) to afford 14a (1.083 g, 3.85 mmol, 36% yield) as a clear colourless oil. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.16H.sub.22O.sub.4Na: 301.1416, found 301.1415.

[0154] 12-(benzyloxy)-12-oxododecanoic acid (14b): Following general method D, 14b was obtained from 13b (2.00 g, 8.68 mmol) and benzyl bromide (1.03 mL, 8.68 mmol). The crude product was purified by column chromatography (50% EtOAc in hexane) to afford 14b (0.998 g, 2.99 mmol, 34% yield) as a clear colourless oil. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.19H.sub.28O.sub.4Na: 343.1885, found 343.1887.

[0155] 14-(benzyloxy)-14-oxotetradecanoic acid (14c): Following general method D, 14c was obtained from 13c (1.50 g, 5.81 mmol) and benzyl bromide (0.69 mL, 5.81 mmol). The crude product was purified by column chromatography (50% EtOAc in hexane) to afford 14c (0.628 g, 1.78 mmol, 31% yield) as a clear colourless oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.21H.sub.33O.sub.4: 349.2379, found 349.2374.

[0156] 3-oxo-1-phenyl-2,5,8,11-tetraoxatridecan-13-oic acid (16): Following general method D, 16 was obtained from 15 (1.00 g, 3.15 mmol) and benzyl bromide (0.37 mL, 3.15 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 16 (0.484 g, 1.53 mmol, 49% yield) as a clear yellow oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.15H.sub.21O.sub.7: 313.1287, found 313.1290.

[0157] Bi-tert-butyl 2,2′-(hexane-1,6-diylbis(oxy))diacetate (17): Hexane-1,6-diol (1.50 g, 12.69 mmol) was dissolved in DCM (52 ml) before tert-butyl 2-bromoacetate (15.0 ml, 102.28 mmol) was added dropwise, followed by the addition of tetra-n-butylammonium bromide (4.50 g, 13.96 mmol). The reaction mixture was then cooled to 0° C. before NaOH (37% w/w, 52 ml) was added. The reaction mixture was then allowed to stir vigorously at room temperature for 16 hours. The crude reaction mixture was biphasic and the organic layer (top layer) was yellow in colour. The organic layer was separated then the aqueous layer was washed with DCM (3×15 ml). The organic layers were combined, dried over MgSO.sub.4 before being filtered and concentrated in vacuo to yield a clear pale yellow oil (6.87 g), which slowly crystallised. The crude product was purified by column chromatography (1% MeOH in DCM) to afford 17 (1.015 g, 2.90 mmol, 23% yield) as a clear colourless oil. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.18H.sub.34O.sub.6Na: 369.2253, found 369.2255.

[0158] Di-tert-butyl 2,2′-(nonane-1,9-diylbis(oxy))diacetate (18) and tert-butyl 2-((9-hydroxynonyl)oxy)acetate (19): Nonane-1,9-diol (2.00 g, 12.48 mmol) was dissolved in DCM (50 ml) before tert-butyl 2-bromoacetate (5.53 ml, 37.44 mmol) was added dropwise, followed by the addition of tetra-n-butylammonium bromide (4-43 g, 13.73 mmol). The reaction mixture was then cooled to 0° C. before NaOH (37% w/w, 50 ml) was added. The reaction mixture was then allowed to stir vigorously at room temperature for 16 hours. The crude reaction mixture was biphasic and the organic layer (top layer) was pale yellow in colour. The organic layer was separated then the aqueous layer was washed with DCM (3×15 ml). The organic layers were combined, dried over MgSO.sub.4 before being filtered and concentrated in vacuo to yield a clear pale yellow oil. The crude product was purified by column chromatography (10-30% EtOAc in hexane) to afford 18 (2.80 g, 7.14 mmol, 57% yield) and 19 (1.387 g, 5.01 mmol, 40% yield) as clear colourless oils. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.15H.sub.30O.sub.4Na: 297.2042, found 297.2046.

[0159] 2,2′-(hexane-1,6-diylbis(oxy))diacetic acid (20a): TFA (0.4 mL) was added to a stirring solution of 17 (0.460 g, 1.33 mmol) in DCM (2 mL) and the resulting reaction mixture stirred at room temperature for 4 hours. The reaction mixture was concentrated in vacuo to afford 20a (319.0 mg, 1.36 mmol, 99% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.10H.sub.19O.sub.6: 235.1182, found 235.1182.

[0160] 2,2′-(nonane-1,9-diylbis(oxy))diacetic acid (20b): TFA (3 mL) was added to a stirring solution of 18 (1.55 g, 3-99 mmol) in DCM (3 mL) and the resulting reaction mixture stirred at room temperature for 4.5 hours. The reaction mixture was concentrated in vacuo to afford 20b (1.09 g, mmol, 3.95 mmol, 99% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.13H.sub.25O.sub.6: 277.1651, found 277.1656.

[0161] 2-((6-(2-(benzyloxy)-2-oxoethoxy)hexyl)oxy)acetic acid (21a): Following general method D, 21a was obtained from 20a (0.304 g, 1.30 mmol) and benzyl bromide (0.15 mL, 1.30 mmol). The crude product was purified by column chromatography (0-100% EtOAc in hexane) to afford 21a (0.110 g, 0.34 mmol, 26% yield) as a yellow oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.17H.sub.25O.sub.6: 325.1651, found 325.1659.

[0162] 2-((9-(2-(benzyloxy)-2-oxoethoxy)nonyl)oxy)acetic acid (21b): Following general method D, 21b was obtained from 20b (1.047 g, 3.79 mmol) and benzyl bromide (0.45 mL, 3.79 mmol). The crude product was purified by column chromatography (0-50% EtOAc in hexane) to afford 21b (0.463 g, 1.24 mmol, 33% yield) as a clear pale yellow oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.20H.sub.31O.sub.6: 367.2121, found 367.2121.

[0163] 9-(2-(tert-butoxy)-2-oxoethoxy)nonanoic acid (22): Pyridinium dichromate (685-5 mg, 1.822 mmol) was added portionwise to a solution of 19 (100.0 mg, 0.364 mmol) in dry DMF (2 mL) and stirred at room temperature for 6 hours. The reaction mixture was diluted with 10% citric acid solution (30 mL) and extracted with EtOAc (4×20 mL). The combined organic layers were washed with sat. NaCl (3×30 mL), dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo to afford 22 (109.8 mg, 0.361 mmol, 99% yield) as a pale yellow oil. HRMS (ESI −ve, Direct Infusion) m/z: [M−H].sup.− calculated for C.sub.15H.sub.27O.sub.5: 287.1858, found 287.1862.

[0164] Benzyl 9-(2-(tert-butoxy)-2-oxoethoxy)nonanoate (23): To a solution of 22 (215.3 mg, 0.747 mmol) in 1,4-dioxane/DMF (1:1, 8 mL), was added benzyl bromide (0.10 mL, 0.821 mmol) followed by the addition of NEt.sub.3 (0.12 mL, 0.885 mmol), then the resultant mixture was stirred at room temperature for 5 hours. The reaction mixture was concentrated in vacuo to afford a yellow oil, then the crude product was purified by column chromatography (0-40% EtOAc in hexane) to afford 23 (159.9 mg, 0.418 mmol, 56% yield) as a clear pale yellow oil. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.22H.sub.34O.sub.5Na: 401.2304, found 401.2303.

[0165] 2-((9-(benzyloxy)-9-oxononyl)oxy)acetic acid (24): TFA (1 mL) was added to a stirring solution of 23 (159.9 mg, 0.422) in DCM (2 mL) and the resulting reaction mixture stirred at room temperature for 4 hours. The reaction mixture was concentrated in vacuo to afford 24 (132.5 mg, 0.407 mmol, 98% yield) as a clear colourless oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.18H.sub.27O.sub.5: 323.1858, found 323.1862.

Synthesis of HDACi-Linker Conjugates with VHL Ligand

##STR00040## ##STR00041##

[0166] Benzyl 12-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-12-oxododecanoate (25a): Following general method E, 25a was obtained from 14a (257 mg, 0.802 mmol) and 11a (200 mg, 0.611 mmol). The crude product was purified by column chromatography (50% EtOAc in hexane) to give 25a (274 mg, 0.430 mmol, 70% yield) as a pale yellow solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.37H.sub.47N.sub.3O.sub.6Na: 652.3363, found 652.3364.

[0167] Benzyl 9-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-9-oxononanoate (25b): Following general method E, 25b was obtained from 14b (0.475 g, 1.71 mmol) and 11a (0.430 g, 1.31 mmol). The crude product was purified by column chromatography (0-50% EtOAc in hexane) to give 25b (0.540 g, 0.94 mmol, 53% yield) as a yellow tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.34H.sub.42N.sub.3O.sub.6: 588.3074, found 588.3067.

[0168] Benzyl 14-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-14-oxotetradecanoate (25c): Following general method E, 25c was obtained from 14c (421.4 mg, 1.21 mmol) and 11a (300.0 mg, 0.92 mmol). The crude product was purified by column chromatography (0-50% EtOAc in hexane) to give 25c (372.4 mg, 0.56 mmol, 61% yield) as a yellow solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.39H.sub.52N.sub.3O.sub.6: 658.3856, found 658.3880.

[0169] Benzyl 2-((6-(2-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)hexyl)oxy)acetate (25d): Following general method E, 25d was obtained from 21a (78.2 mg, 0.241 mmol) and 11a (71.8 mg, 0.219 mmol). The crude product was purified by column chromatography (0-100% EtOAc in hexane) to afford 25d (76.5 mg, 0.120 mmol, 55% yield) as a pale yellow oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.35H.sub.44N.sub.3O.sub.8: 634.3128, found 634.3125.

[0170] Tert-butyl 2-((9-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-9-oxononyl)oxy)acetate (25e): Following general method E, 25e was obtained from 22 (85.0 mg, 0.295 mmol) and 11a (88.4 mg, 0.270 mmol). The crude product was purified by column chromatography (0-100% EtOAc in hexane) to afford 25e (66.3 mg, 0.110 mmol, 41% yield) as a yellow tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.33H.sub.48N.sub.3O.sub.7: 598.3492, found 598.3484.

[0171] Benzyl 9-(2-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonanoate (25f): Following general method E, 25f was obtained from 24 (130.0 mg, 0.403 mmol) and 11a (110.0 mg, 0.336 mmol). The crude product was purified by column chromatography (0-100% EtOAc in hexane) to afford 25f (157.4 mg, 0.247 mmol, 73% yield) as a clear colourless tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.36H.sub.46N.sub.3O.sub.7: 632.3336, found 632.3335.

[0172] Benzyl 2-((9-(2-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonyl)oxy)acetate (25g): Following general method E, 25g was obtained from 21b (145.0 mg, 0.396 mmol) and 11a (99.6 mg, 0.304 mmol). The crude product was purified by column chromatography (0-70% EtOAc in hexane) to afford 259 (157.8 mg, 0.229 mmol, 75% yield) as a clear colourless tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.38H.sub.50N.sub.3O.sub.8: 676.3598, found 676.3605.

[0173] Benzyl 12-((4-((2-((tert-butoxycarbonyl)amino)-4-fluorophenyl)carbamoyl)phenyl)amino)-12-oxododecanoate (25h): Following general method E, 25h was obtained from 14a (246.4 mg, 0.767 mmol) in and 11b (201.8 mg, 0.584 mmol). The crude product was purified by column chromatography (10-80% EtOAc in hexane) to give 25h (332.4 mg, 0.508 mmol, 87% yield) as a dark orange tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.37H.sub.47FN.sub.3O.sub.6: 648.3449, found 648.3452.

[0174] Benzyl 2-((9-(2-((4-((2-((tert-butoxycarbonyl)amino)-4-fluorophenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonyl)oxy)acetate (25i): Following general method E, 25i was obtained from 21b (167.7 mg, 0.458 mmol) and 11b (120.0 mg, 0.347 mmol). The crude product was purified by column chromatography (25-30% EtOAc in hexane) to afford 25i (114.8 mg, 0.164 mmol, 42% yield) as an orange tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.38H.sub.49FN.sub.3O.sub.8: 694.3504, found 694.3517.

[0175] Benzyl 2-(2-(2-(2-((4-((2-((tert-butoxycarbonyl)amino)-5-(thiophen-2-yl)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)ethoxy)ethoxy)acetate (25j): Following general method E, 25j was obtained from 16 (114.0 mg, 0.362 mmol) and 11c (114.0 mg, 0.278 mmol). The crude product was purified by column chromatography (0-100% EtOAc in hexane, product eluted at 80-90% EtOAc) to afford 25i (117.5 mg, 0.162 mmol, 58% yield) as a dark yellow tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.37H.sub.42N.sub.3O.sub.9S: 704.2642, found 704.2637.

[0176] 12-((4-((2-((Tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-12-oxododecanoic acid (26a): Following general method F, benzyl ester hydrogenolysis of 25a (171 mg, 0.271 mmol) was performed to afford 26a (146 mg, 0.266 mmol, 98% yield) as an off-white solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.30H.sub.41N.sub.3O.sub.6Na: 562.2893, found 562.2886.

[0177] 9-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-9-oxononanoic acid (26b): Following general method F, benzyl ester hydrogenolysis of 25b (370.8 mg, 0.63 mmol) was performed to afford 26b (295.1 mg, 0.59 mmol, 93% yield) as a white crystalline solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.27H.sub.36N.sub.3O.sub.6: 498.2604, found 498.2597.

[0178] 14-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-14-oxotetradecanoic acid (26c): Following general method F, benzyl ester hydrogenolysis of 25c (348.6 mg, 0.530 mmol) was performed to afford 26c (302.0 mg, 0.527 mmol, 99% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.32H.sub.46N.sub.3O.sub.6: 568.3387, found 568.3391.

[0179] 2-((6-(2-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)hex yl)oxy)acetic acid (26d): Following general method F, benzyl ester hydrogenolysis of 25d (76.5 mg, 0.121 mmol) was performed to afford 26d (65.8 mg, 0.120 mmol, 99% yield) as a clear colourless oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.28H.sub.38N.sub.3O.sub.8: 544.2659, found 544.2645.

[0180] 2-((9-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-9-oxononyl)oxy)acetic acid (26e): To a solution of 25e (62.7 mg, 0.111 mmol) in DCM (2.7 mL) a solution of NaOH in MeOH (4M, 0.3 mL) was added. The reaction was stirred at room temperature for 16 h. The reaction mixture was concentrated in vacuo, then redissolved in water (10 mL) and acidified with HCl (3M, ca. 1 mL) to pH 2. The product was then extracted in EtOAc (2×20 mL), dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo to afford 26e as a yellow solid (55.4 mg, 0.101 mmol, 91% yield). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.29H.sub.40N.sub.3O.sub.7: 542.2866, found 542.2861.

[0181] 9-(2-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonanoic acid (26f): Following general method F, benzyl ester hydrogenolysis of 25f (120.2 mg, 0.190 mmol) was performed to afford 26f (105.6 mg, 0.189 mmol, 99% yield) as a clear colourless tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.29H.sub.40N.sub.3O.sub.7: 542.2866, found 542.2863.

[0182] 2-((9-(2-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)non yl)oxy)acetic acid (26g): Following general method F, benzyl ester hydrogenolysis of 25g (134.8 mg, 0.199 mmol) was performed to afford 26g (118.7 mg, 0.199 mmol, 100% yield) as a clear colourless tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.31H.sub.44N.sub.3O.sub.8: 586.3128, found 586.3128.

[0183] 12-((4-((2-((tert-butoxycarbonyl)amino)-4-fluorophenyl)carbamoyl)phenyl)amino)-12-oxododecanoic acid (26h): Following general method F, benzyl ester hydrogenolysis of 25h (219.6 mg, 0.339 mmol) was performed to afford 26h (192.9 mg, 0.266 mmol, 98% yield) as a pale purple/brown solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.30H.sub.41FN.sub.3O.sub.6: 558.2979, found 558.2974.

[0184] 2-((9-(2-((4-((2-((tert-butoxycarbonyl)amino)-4-fluorophenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonyl)oxy)acetic acid (26i): Following general method F, benzyl ester hydrogenolysis of 25i (114.0 mg, 0.164 mmol) was performed to afford 26i (99.8 mg, 0.164 mmol, 100% yield) as a yellow/brown tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.31H.sub.43FN.sub.3O.sub.8: 604.3034, found 604.3046.

[0185] 2-(2-(2-(2-((4-((2-((tert-butoxycarbonyl)amino)-5-(thiophen-2-yl)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)ethoxy)ethoxy)acetic acid (26j): To a solution of 25j (111.6 mg, 0.159 mmol) in MeOH (10 mL) was added NaOH (160 mg) until solution reached pH 10 (0.4 M NaOH in MeOH), then the resultant solution stirred at room temperature for 4 hours. The reaction mixture was concentrated in vacuo, then dissolved in water (10 mL) and washed with EtOAC (20 mL). The aqueous layer was acidified to pH2 with HCl (1M) and the product was extracted with EtOAc (2×20 mL), then the combined organic layers dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo to afford 26j (96.7 mg, 0.154 mmol, 87% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.30H.sub.36N.sub.3O.sub.9S: 614.2172, found 614.2161.

[0186] Tert-butyl(2-(4-(12-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-12-oxododecanamido)benzamido)phenyl)carbamate (27a): Following general method G, 27a was obtained from 26a (65.5 mg, 0.121 mmol) and VH_032 amine (50.0 mg, 0.099 mmol). The crude product was purified by column chromatography (0-5% MeOH in DCM) to afford 27a (61.9 mg, 0.064 mmol, 64% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.52H.sub.70N.sub.7O.sub.8S: 952.5007, found 952.5009.

[0187] Tert-butyl (2-(4-(9-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-9-oxononanamido)benzamido)phenyl)carbamate (27b): Following general method G, 27b was obtained from 26b (59.9 mg, 0.120 mmol) and VH_032 amine (50.0 mg, 0.099 mmol). The crude product was purified by column chromatography (0-5% MeOH in DCM) to afford 27b (76.1 mg, 0.083 mmol, 84% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.49H.sub.64N.sub.7O.sub.8S: 910.4537, found 910.4529.

[0188] Tert-butyl (2-(4-(14-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-14-oxotetradecanamido)benzamido)phenyl)carbamate (27c): Following general method G, 27c was obtained from 26c (53.5 mg, 0.094 mmol) and VH_032 amine (40.0 mg, 0.080 mmol). The crude product was purified by column chromatography (0-5% MeOH in DCM) to afford 27c (62.5 mg, 0.063 mmol, 79% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.54H.sub.74N.sub.7O.sub.8S: 980.5320, found 980.5303.

[0189] Tert-butyl (2-(4-(2-((6-(2-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-2-oxoethoxy)hexyl)oxy)acetamido)benz amido)phenyl)carbamate (27d): Following general method G, 27d was obtained from 26d (67.2 mg, 0.124 mmol) and VH_032 amine (50.0 mg, 0.099 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 27d (92.4 mg, 0.093 mmol, 94% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.50H.sub.66N.sub.7O.sub.11S: 956.4592, found 956.4590.

[0190] Tert-butyl (2-(4-(9-(2-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl) pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-2-oxoethoxy)nonanamido)benzamido)phenyl)carbamate (27e): Following general method G, 27e was obtained from 26e (52.3 mg, 0.099 mmol) and VH_032 amine (40.0 mg, 0.080 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 27e (68.4 mg, 0.071 mmol, 89% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.51H.sub.68N.sub.7O.sub.9S: 954.4799, found 954.4798.

[0191] Tert-butyl (2-(4-(2-((9-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl) pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-9-oxononyl)oxy)acetamido)benzamido)phenyl)carbamate (27f): Following general method G, 27f was obtained from 26f (52.8 mg, 0.097 mmol) and VH_032 amine (40.0 mg, 0.080 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 27f (72.9, 0.076 mmol, 95% yield) as a pale yellow/white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.51H.sub.68N.sub.7O.sub.9S: 954.4799, found 954.4792.

[0192] Tert-butyl (2-(4-(2-((9-(2-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-2-oxoethoxy)nonyl)oxy)acetamido)benz amido)phenyl)carbamate (27g): Following general method G, 27g was obtained from 26g (56.2 mg, 0.096 mmol) and VH_032 amine (40.0 mg, 0.080 mmol). The crude product was purified by column chromatography (0-8% MeOH in DCM) to afford 27g (68.4 mg, 0.068 mmol, 85% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.53H.sub.72N.sub.7O.sub.10S: 998.5061, found 998.5048.

[0193] Tert-butyl (5-fluoro-2-(4-(12-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl) pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-12-oxododecanamido)benzamido)phenyl) carbamate (27h): Following general method G, 27h was obtained from 26h (53.2 mg, 0.095 mmol) and VH_032 amine (40.0 mg, 0.080 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 27h (58.7 mg, 0.060 mmol, 75% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.52H.sub.69FN.sub.7O.sub.8S: 970.4912, found 970.4913.

[0194] Tert-butyl (5-fluoro-2-(4-(2-((9-(2-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl) carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-2-oxoethoxy)nonyl)oxy)acetamido)benzamido)phenyl)carbamate (27i): Following general method G, 27i was obtained from 26i (57.6 mg, 0.096 mmol) and VH_032 amine (40.0 mg, 0.080 mmol). The crude product was purified by column chromatography (0-8% MeOH in DCM) to afford 27i (75.7, 0.072 mmol, 90% yield) as a pale yellow/white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.53H.sub.71FN.sub.7O.sub.10S: 1016.4967, found 1016.4928.

[0195] Tert-butyl (2-(4-((S)-13-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidine-1-carbonyl)-14,14-dimethyl-11-oxo-3,6,9-trioxa-12-azapentadecanamido)benzamido)-4-(thiophen-2-yl)phenyl)carbamate (27j): Following general method G, 27j was obtained from 26j (35.1 mg, 0.057 mmol) and VH_032 amine (24.0 mg, 0.048 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 27j (30.3 mg, 0.029 mmol, 61% yield) as a yellow tar. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.52H.sub.64N.sub.7O.sub.11S.sub.2: 1026.4105, found 1026.4066.

##STR00042##

[0196] N1-(4-((2-aminophenyl)carbamoyl)phenyl)-N12-((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)dodecanediamide (PROTAC4): Following general method H, Boc deprotection of 27a (37.6 mg, 0.0395 mmol) was performed to afford PROTAC4 (25.8 mg, 0.0288 mmol, 73% yield) as a pale yellow solid. Prior to biological evaluation the PROTAC was further purified by semi-preparative HPLC (5-95% MeCN in H.sub.2O, 260 nm, 45 min gradient). .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 39-CH), 7.95 (d, J=8.8 Hz, 2H, 15-CH), 7.72 (d, J=8.8 Hz, 2H, 14-CH), 7.43-7.48 (m, 2H, 36-CH), 7.38-7.42 (m, 2H, 35-CH), 7.18 (dd, J=7.8, 1.3 Hz, 1H, 23-CH), 7.07 (app. td, J=7.8, 1.3 Hz, 1H, 21-CH), 6.90 (dd, J=7.8, 1.3 Hz, 1H, 20-CH), 6.76 (app. td, J=7.8, 1.3 Hz, 1H, 22-CH), 4.60-4.66 (m, 1H, 24-CH), 4.55-4.60 (m, 1H, 31-CH), 4.50-4.55 (m, 1H, 33-CH), 4.47-4.50 (m, 1H, 29-CH), 4.31-4.39 (m, 1H, 33-CH), 3.86-3.93 (m, 1H, 28-CH), 3.76-3.83 (m, 1H, 28-CH), 2.47 (s, 3H, 41-CH.sub.3), 2.40 (t, J=7.5 Hz, 2H, 11-CH.sub.2), 2.18-2.33 (m, 3H, 2-CH.sub.2, 30-CH), 2.03-2.12 (m, 1H, 30-CH), 1.70 (quin, J=7.5 Hz, 2H, 10-CH.sub.2), 1.53-1.64 (m, 2H, 3-CH.sub.2), 1.28-1.41 (m, 12H, (4-9)-CH.sub.2), 1.03 (s, 9H, 26-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.47H.sub.62N.sub.7O.sub.6S: 852.4476, found 852.4482.

##STR00043##

[0197] N1-(4-((2-aminophenyl)carbamoyl)phenyl)-N9-((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)nonanediamide (PROTAC6): Following general method H, Boc deprotection of 27b (37.6 mg, 0.0395 mmol) was performed to afford PROTAC6 (37.0 mg, 0.044 mmol, 99% yield) as an off-white solid. Prior to biological evaluation the PROTAC was further purified by semi-preparative HPLC (5-95% MeCN in H.sub.2O, 260 nm, 45 min gradient). .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 36-CH), 7.95 (d, J=8.7 Hz, 2H, 12-CH), 7.71 (d, J=8.7 Hz, 2H, 11-CH), 7.45 (d, J=8.4 Hz, 2H, 33-CH), 7.40 (d, J=8.4 Hz, 2H, 32-CH), 7.18 (app. dd, J=7.8, 1.3 Hz, 1H, 20-CH), 7.07 (app. td, J=7.8, 1.3 Hz, 1H, 18-CH), 6.90 (app. dd, J=7.8, 1.3 Hz, 1H, 17-CH), 6.76 (app. td, J=7.8, 1.3 Hz, 1H, 19-CH), 4.63 (s, 1H, 21-CH), 4.55-4.61 (m, 1H, 28-CH), 4.50-4.55 (m, 1H, 30-CH), 4.47-4.50 (m, 1H, 29-CH), 4.31-4.38 (m, 1H, 30-CH), 3.87-3.94 (m, 1H, 25-CH), 3.76-3.83 (m, 1H, 25-CH), 2.46 (s, 3H, 38-CH.sub.3), 2.39 (t, J=7.5 Hz, 2H, 8-CH.sub.3), 2.17-2.33 (m, 3H, 2-CH.sub.2, 27-CH), 2.03-2.11 (m, 1H, 27-CH), 1.70 (quin, J=7.5 Hz, 2H, 7-CH.sub.2), 1.61 (quin, J=6.9 Hz, 2H, 3-CH.sub.2), 1.27-1.44 (m, 6H, (4-6)-CH.sub.2), 1.03 (s, 9H, 23-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.44H.sub.56N.sub.7O.sub.6S: 810.4013, found 810.4005.

##STR00044##

[0198] N1-(4-((2-aminophenyl)carbamoyl)phenyl)-N14-((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)tetradecanediamide (PROTAC34): Following general method H, Boc deprotection of 27c (62.5 mg, 0.064 mmol) was performed to afford PROTAC34 (51.6 mg, 0.058 mmol, 91% yield) as a white solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 41, CH), 7.95 (d, J=8.7 Hz, 2H, 17-CH), 7.72 (d, J=8.7 Hz, 2H, 16-CH), 7.43-7.47 (m, 2H, 38-CH), 7.38-7.43 (m, 2H, 37-CH), 7.18 (dd, J=7.8, 1.3 Hz, 1H, 25-CH), 7.06 (app. td, J=7.8, 1.3 Hz, 1H, 23-CH), 6.90 (dd, J=7.8, 1.3 Hz, 1H, 22-CH), 6.76 (app. td, J=7.8, 1.3 Hz, 1H, 24-CH), 4.63 (s, 1H, 26-CH), 4.55-4.60 (m, 1H, 33-CH), 4.52 (d, J=15.5 Hz, 1H, 35-CH), 4.46-4.50 (m, 1H, 31-CH), 4.34 (d, J=15.5 Hz, 1H, 35-CH), 3.86-3.93 (m, 1H, 30-CH), 3.75-3.82 (m, 1H, 30-CH), 2.46 (s, 3H, 43-CH.sub.3), 2.39 (t, J=7.4 Hz, 2H, 13-CH.sub.2), 2.17-2.32 (m, 3H, 2-CH.sub.2,32-CH), 2.03-2.11 (m, 1H, 32-CH), 1.70 (quin, J=7.4 Hz, 2H, 12-CH.sub.2), 1.52-1.65 (m, 2H, 3-CH.sub.2), 1.27-1.39 (m, 16H, (4-11)-CH.sub.2), 1.03 (s, 9H, 28-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.49H.sub.66N.sub.7O.sub.6S: 880.4795, found 880.4762.

##STR00045##

[0199] (2S,4R)-1-((S)-2-(2-((6-(2-((4-((2-aminophenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)hexyl)oxy)acetamido)-3,3-dimethylbutanoyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (PROTAC12): Following general method H, Boc deprotection of 27d (86.3 mg, 0.090 mmol) was performed to afford PROTAC12 (71.7 mg, 0.083 mmol, 90% yield) as a pale yellow solid. Prior to biological evaluation the PROTAC was further purified by semi-preparative HPLC (5-95% MeCN in H.sub.2O, 260 nm, 45 min gradient). .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.85 (s, 1H, 37-CH), 7.96 (d, J=8.6 Hz, 2H, 13-CH), 7.75 (d, J=8.6 Hz, 2H, 12-CH), 7.42-7.45 (m, 2H, 34-CH), 7.37-7.41 (m, 2H, 33-CH), 7.18 (dd, J=7.7, 1.1 Hz, 1H, 21-CH), 7.07 (td, J=7.7, 1.1 Hz, 1H, 19-CH), 6.89 (dd, J=7.7, 1.1 Hz, 1H, 18-CH), 6.76 (td, J=7.7, 1.1 Hz, 1H, 20-CH), 4.69 (s, 1H, 22-CH), 4.55-4.62 (m, 1H, 29-CH), 4.45-4.55 (m, 2H, 27,31-CH), 4.31-4.38 (m, 1H, 31-CH), 4.05-4.11 (m, 2H, 9-CH.sub.2), 3.95-4.00 (m, 1H, 2-CH), 3.89-3.94 (m, 1H, 2-CH), 3.83-3.89 (m, 1H, 26-CH), 3.75-3.82 (m, 1H, 26-CH), 3.53-3.62 (m, 4H, 3,8-CH.sub.2), 2.46 (s, 3H, 39-CH.sub.3), 2.18-2.27 (m, 1H, 28-CH), 2.03-2.13 (m, 1H, 28-CH), 1.62-1.73 (m, 4H, 4,7-CH.sub.2), 1.42-1.52 (m, 4H, 5,6-CH.sub.2), 1.03 (s, 9H, 24-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.45H.sub.58N.sub.7O.sub.8S: 856.4068, found 856.4064.

##STR00046##

[0200] (2S,4R)-1-((S)-2-(2-((9-((4-((2-aminophenyl)carbamoyl)phenyl)amino)-9-oxononyl)oxy)acetamido)-3,3-dimethylbutanoyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (PROTAC13): Following general method H, Boc deprotection of 27e (66.9 mg, 0.070 mmol) was performed to afford PROTAC13 (52.5 mg, 0.060 mmol, 86% yield) as a pale yellow solid. Prior to biological evaluation the PROTAC was further purified by semi-preparative HPLC (5-95% MeCN in H.sub.2O, 260 nm, 45 min gradient). .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.85 (s, 1H, 38-CH), 7.94 (d, J=8.7 Hz, 2H, 14-CH), 7.72 (d, J=8.7 Hz, 2H, 13-CH), 7.43-7.47 (m, 2H, 35-CH), 7.37-7.42 (m, 2H, 34-CH), 7.17 (dd, J=7.7, 1.1 Hz, 1H, 22-CH), 7.07 (app. td, J=7.7, 1.1 Hz, 1H, 20-CH), 6.89 (dd, J=7.7, 1.1 Hz, 1H, 19-CH), 6.76 (app. td, J=7.7, 1.1 Hz, 1H, 21-CH), 4.69 (s, 1H, 23-CH), 4.56-4.63 (m, 1H, 30-CH), 4.47-4.55 (m, 2H, 28,32-CH), 4.35 (d, J=15.5 Hz, 1H, 32-CH), 3.94-3.99 (m, 1H, 2-CH), 3.89-3.94 (m, 1H, 2-CH), 3.84-3.89 (m, 1H, 27-CH), 3.76-3.82 (m, 1H, 27-CH), 3.53 (t, J=6.3 Hz, 2H, 3-CH.sub.2), 2.46 (s, 3H, 40-CH.sub.3), 2.37 (t, J=7.5 Hz, 2H, 10-CH.sub.2), 2.19-2.27 (m, 1H, 29-CH), 2.04-2.12 (m, 1H, 29-CH), 1.59-1.71 (m, 4H, 4,9-CH.sub.2), 1.33-1.43 (m, 8H, (5-8)-CH.sub.2), 1.03 (s, 9H, 25-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.46H.sub.60N.sub.7O.sub.7S: 854.4275, found 854.4277.

##STR00047##

[0201] (2S,4R)-1-((S)-2-(9-(2-((4-((2-aminophenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonanamido)-3,3-dimethylbutanoyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (PROTAC14): Following general method H, Boc deprotection of 27f (60.2 mg, 0.063 mmol) was performed to afford PROTAC14 (50.6 mg, 0.059 mmol, 93% yield) as a pale yellow solid. Prior to biological evaluation the PROTAC was further purified by semi-preparative HPLC (5-95% MeCN in H.sub.2O, 260 nm, 45 min gradient). .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 38-CH), 7.98 (d, J=8.7 Hz, 2H, 14-CH), 7.77 (d, J=8.7 Hz, 2H, 13-CH), 7.45 (d, J=8.3 Hz, 2H, 35-CH), 7.41 (d, J=8.3 Hz, 2H, 34-CH), 7.18 (dd, J=7.6, 1.3 Hz, 1H, 22-CH), 7.07 (app. td, J=7.6, 1.3 Hz, 1H, 20-CH), 6.90 (dd, J=7.6, 1.3 Hz, 1H, 19-CH), 6.77 (app. td, J=7.6, 1.3 Hz, 1H, 21-CH), 4.63 (s, 1H, 23-CH), 4.56-4.59 (m, 1H, 30-CH), 4.52 (d, J=15.5 Hz, 1H, 32-CH), 4.46-4.50 (m, 1H, 28-CH), 4.35 (d, J=15.5 Hz, 1H, 32-CH), 4.09 (s, 2H, 10-CH.sub.2), 3.86-3.92 (m, 1H, 27-CH), 3.76-3.82 (m, 1H, 27-CH), 3.60 (t, J=6.6 Hz, 2H, 9-CH.sub.2), 2.47 (s, 3H, 40-CH.sub.3), 2.18-2.32 (m, 3H, 2-CH.sub.2,29-CH), 2.03-2.12 (m, 1H, 29-CH), 1.68 (quin, J=6.6 Hz, 2H, 8-CH.sub.2), 1.56-1.64 (m, 2H, 3-CH.sub.2), 1.32-1.45 (m, 8H, (4-7)-CH.sub.2), 1.03 (s, 9H, 25-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.46H.sub.60N.sub.7O.sub.7S: 854.4275, found 854.4268.

##STR00048##

[0202] (2S,4R)-1-((S)-2-(2-((9-(2-((4-((2-aminophenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonyl)oxy)acetamido)-3,3-dimethylbutanoyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (PROTAC16): Following general method H, Boc deprotection of 27g (66.7 mg, 0.067 mmol) was performed to afford PROTAC16 (58.2 mg, 0.064 mmol, 96% yield) as a pale yellow solid. Prior to biological evaluation the PROTAC was further purified by semi-preparative HPLC (5-95% MeCN in H.sub.2O, 260 nm, 45 min gradient). .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 40-CH), 7.97 (d, J=8.6 Hz, 2H, 16-CH), 7.76 (d, J=8.6 Hz, 2H, 15-CH), 7.45 (d, J=8.3 Hz, 2H, 37-CH), 7.39 (d, J=8.3 Hz, 2H, 36-CH), 7.18 (dd, J=7.7, 1.1 Hz, 1H, 24-CH), 7.07 (app. td, J=7.7, 1.1 Hz, 1H, 22-CH), 6.90 (dd, J=7.7, 1.1 Hz, 1H, 21-CH), 6.76 (app. td, J=7.7, 1.1 Hz, 1H, 23-CH), 4.69 (s, 1H, 25-CH), 4.56-4.61 (m, 1H, 32-CH), 4.53 (d, J=15.5 Hz, 1H, 34-CH), 4.46-4.50 (m, 1H, 30-CH), 4.34 (d, J=15.5 Hz, 1H, 34-CH), 4.07 (s, 2H, 12-CH.sub.2), 3.97 (d, J=15.4 Hz, 1H, 2-CH.sub.2), 3.92 (d, J=15.4 Hz, 1H, 2-CH.sub.2), 3.83-3.90 (m, 1H, 29-CH), 3.75-3.82 (m, 1H, 29-CH), 3.50-3.59 (m, 4H, 3,11-CH.sub.2), 2.46 (s, 3H, 42-CH.sub.3), 2.17-2.26 (m, 1H, 31-CH), 2.03-2.11 (m, 1H, 31-CH), 1.59-1.69 (m, 4H, 4,10-CH.sub.2), 1.32-1.44 (m, 10H, (5-9)-CH.sub.2), 1.03 (s, 9H, 27-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.48H.sub.64N.sub.7O.sub.8S: 898.4537, found 898.4531.

##STR00049##

[0203] N1-(4-((2-amino-4-fluorophenyl)carbamoyl)phenyl)-N12-((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)dodecanediamide (PROTAC17): Following general method H, Boc deprotection of 27h (58.7 mg, 0.061 mmol) was performed to afford PROTAC17 (49.2 mg, 0.056 mmol, 92% yield) as a pale yellow solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 39-CH), 7.94 (d, J=8.7 Hz, 2H, 15-CH), 7.72 (d, J=8.7 Hz, 2H, 14-CH), 7.43-7.47 (m, 2H, 36-CH), 7.37-7.42 (m, 2H, 35-CH), 7.11 (dd, J.sub.HH=8.6, J.sub.HF=6.0 Hz, 1H, 23-CH), 6.58 (dd, J.sub.HF=10.7, J.sub.HH=2.8 Hz, 1H, 20-CH), 6.41 (app. td, J.sub.HF=8.6, J.sub.HH=8.6, 2.8 Hz, 1H, 22-CH), 4.63 (s, 1H, 24-CH), 4.55-4.60 (m, 1H, 31-CH), 4.52 (d, J=15.5 Hz, 1H, 33-CH), 4.47-4.50 (m, 1H, 29-CH), 4.35 (d, J=15.5 Hz, 1H, 33-CH), 3.86-3.93 (m, 1H, 28-CH), 3.76-3.82 (m, 1H, 28-CH), 2.46 (s, 3H, 41-CH.sub.3), 2.39 (t, J=7.5 Hz, 2H, 11-CH.sub.2), 2.17-2.31 (m, 3H, 2-CH.sub.2,30-CH), 2.03-2.12 (m, 1H, 30-CH), 1.69 (quin, J=7.5 Hz, 2H, 10-CH.sub.2), 1.53-1.63 (m, 2H, 3-CH.sub.2), 1.29-1.37 (m, 12H, (4-9)-CH.sub.2), 1.03 (s, 9H, 26-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.47H.sub.61FN.sub.7O.sub.6S: 870.4388, found 870.4376.

##STR00050##

[0204] (2S,4R)-1-((S)-2-(2-((9-(2-((4-((2-amino-4-fluorophenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)nonyl)oxy)acetamido)-3,3-dimethylbutanoyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (PROTAC20): Following general method H, Boc deprotection of 27i (70.8 mg, 0.070 mmol) was performed to afford PROTAC20 (63.3 mg, 0.068, 98% yield) as a pale brown solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 40-CH), 7.96 (d, J=8.7 Hz, 2H, 16-CH), 7.75 (d, J=8.7 Hz, 2H, 15-CH), 7.42-7.47 (m, 2H, 37-CH), 7.37-7.42 (m, 2H, 36-CH), 7.11 (dd, J.sub.HH=8.6, J.sub.HF=6.1 Hz, 1H, 24-CH), 6.58 (dd, J.sub.HF=10.7, J.sub.HH=2.8 Hz, 1H, 20-CH), 6.41 (td, J.sub.HF=8.6, J.sub.HH=8.6, 2.8 Hz, 1H, 23-CH), 4.68 (s, 1H, 25-CH), 4.59 (dd, J=9.0, 7.8 Hz, 1H, 32-CH), 4.52 (d, J=15.6 Hz, 1H, 34-CH), 4.47-4.50 (m, 1H, 30-CH), 4.34 (d, J=15.6 Hz, 1H, 34-CH), 4.07 (s, 2H, 12-CH.sub.2), 3.95 (d, J=15.4 Hz, 1H, 2-CH.sub.2), 3.94 (d, J=15.4 Hz, 1H, 2-CH.sub.2), 3.84-3.89 (m, 1H, 29-CH), 3.74-3.82 (m, 1H, 29-CH), 3.50-3.59 (m, 4H, (3,11)-CH.sub.2), 2.46 (s, 3H, 42-CH.sub.3), 2.18-2.27 (m, 1H, 31-CH), 2.02-2.12 (m, 1H, 31-CH), 1.58-1.68 (m, 4H, (4,10)-CH.sub.2), 1.32-1.43 (m, 12H, (5-9)-CH.sub.2), 1.03 (s, 9H, 27-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.48H.sub.63FN.sub.7O.sub.8S: 916.4443, found 916.4426.

##STR00051##

[0205] (2S,4R)-1-((S)-14-((4-((2-amino-5-(thiophen-2-yl)phenyl)carbamoyl)phenyl)amino)-2-(tert-butyl)-4,14-dioxo-6,9,12-trioxa-3-azatetradecanoyl)-4-hydroxy-N-(4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (PROTAC22): Following general method H, Boc deprotection of 27j (30.3 mg, 0.029 mmol) was performed to afford PROTAC22 (26.8 mg, 0.029 mmol, 99% yield) as a pale yellow solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.84 (s, 1H, 39-CH), 7.98 (d, J=8.7 Hz, 2H, 11-CH), 7.75 (d, J=8.7 Hz, 2H, 10-CH), 7.49 (d, J=2.1 Hz, 1H, 19-CH), 7.40-7.44 (m, 2H, 36-CH), 7.36-7.39 (m, 2H, 35-CH), 7.34 (dd, J=8.3, 2.1 Hz, 1H, 17-CH), 7.22 (d, J=5.0 Hz, 1H, 23-CH), 7.19 (d, J=3.7 Hz, 1H, 21-CH), 7.01 (dd, J=5.0, 3.7 Hz, 1H, 22-CH), 6.89 (d, J=8.3 Hz, 1H, 16-CH), 4.68 (s, 1H, 24-CH), 4.54-4.60 (m, 1H, 31-CH), 4.51 (d, J=15.5 Hz, 1H, 33-CH), 4.46-4.49 (m, 1H, 29-CH), 4.31 (d, J=15.5 Hz, 1H, 33-CH), 4.15 (d, J=15.8 Hz, 1H, 7-CH), 4.09 (d, J=15.8 Hz, 1H, 7-CH), 4.02 (d, J=15.6 Hz, 1H, 2-CH), 3.91 (d, J=15.6 Hz, 1H, 2-CH), 3.82-3.87 (m, 1H, 28-CH), 3.69-3.81 (m, 9H, 28-CH,(3-6)-CH.sub.2), 2.45 (s, 3H, 41-CH.sub.3), 2.16-2.24 (m, 1H, 30-CH), 2.03-2.11 (m, 1H, 30-CH), 1.02 (s, 9H, 26-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.47H.sub.56N.sub.7O.sub.9S.sub.2: 926.3581, found 926.3556.

Synthesis of HDAC PROTACs Containing Alternative VHL Ligands

[0206] ##STR00052## ##STR00053## ##STR00054##

[0207] Tert-butyl (2-(4-(12-bromododecanamido)benzamido)phenyl)carbamate (29): Following general method E, 29 was obtained from 28 (332.6 mg, 1.19 mmol) and 11a (300.0 mg, 0.92 mmol). The crude product was purified by column chromatography (0-50% EtOAc in hexane) to give 29 (207.0 mg, 0.35 mmol, 38% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.30H.sub.43.sup.81BrN.sub.3O.sub.4: 590.2416, found 590.2411.

[0208] Tert-butyl (2-(4-(12-(2-(((2S,4R)-1-((S)-2-acetamido-3,3-dimethylbutanoyl)-4-hydroxypyrrolidine-2-carboxamido)methyl)-5-(4-methylthiazol-5-yl)phenoxy)dodecanamido)benzamido)phenyl)carbamate (30a): Following general method I, 30a was obtained from (2S,4R)-1-((S)-2-acetamido-3,3-dimethylbutanoyl)-4-hydroxy-N-(2-hydroxy-4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (VH 032 phenol, 17.2 mg, 0.034 mmol) and 29 (20.0 mg, 0.034 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 30a (17.8 mg, 0.018 mmol, 52% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.54H.sub.74N.sub.7O.sub.9S: 996.5269, found 996.5239.

[0209] Tert-butyl (2-(4-(12-(2-(((2S,4R)-1-((S)-2-(1-fluorocyclopropane-1-carboxamido)-3,3-dimethylbutanoyl)-4-hydroxypyrrolidine-2-carboxamido)methyl)-5-(4-methylthiazol-5-yl)phenoxy)dodecanamido)benzamido)phenyl)carbamate (30b): Following general method I, 30b was obtained from (2S,4R)-1-((S)-2-(1-fluorocyclopropane-1-carboxamido)-3,3-dimethylbutanoyl)-4-hydroxy-N-(2-hydroxy-4-(4-methylthiazol-5-yl)benzyl)pyrrolidine-2-carboxamide (VH 101 phenol, 18.6 mg, 0.034 mmol) and 29 (20.0 mg, 0.034 mmol). The crude product was purified by column chromatography (1-10% MeOH in DCM) to afford 30b (24.2 mg, 0.022 mmol, 64% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.56H.sub.75FN.sub.7O.sub.9S: 1040.5331, found 1040.5304.

##STR00055##

[0210] (2S,4R)-1-((S)-2-acetamido-3,3-dimethylbutanoyl)-N-(2-((12-((4-((2-aminophenyl)carbamoyl)phenyl)amino)-12-oxododecyl)oxy)-4-(4-methylthiazol-5-yl)benzyl)-4-hydroxypyrrolidine-2-carboxamide (PROTAC35): Following general method H, Boc deprotection of 30a (17.8 mg, 0.018 mmol) was performed to afford PROTAC35 (16.1 mg, 0.018 mmol, 99% yield) as a white solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) S.sub.H ppm 8.86 (s, 1H, 28-CH), 7.95 (d, J=8.7 Hz, 2H, 15-CH), 7.72 (d, J=8.7 Hz, 2H, 14-CH), 7.47 (d, J=8.2 Hz, 1H, 32-CH), 7.17 (dd, J=7.7, 1-3 Hz, 1H, 23-CH), 7.07 (app. td, J=7.7, 1.3 Hz, 1H, 21-CH), 6.94-7.00 (m, 2H, 25,31-CH), 6.90 (dd, J=7.7, 1.3 Hz, 1H, 20-CH), 6.76 (app. td, J=7.7, 1.3 Hz, 1H, 22-CH), 4.57-4.65 (m, 2H, 36,41-CH), 4.48-4.52 (m, 1H, 38-CH), 4.46 (d, J=16.1 Hz, 1H, 34-CH), 4.39 (d, J=16.1 Hz, 1H, 34-CH), 4.05 (t, J=6.3 Hz, 2H, 1-CH.sub.2), 3.86-3.92 (m, 1H, 39-CH.sub.2), 3.75-3.81 (m, 1H, 39-CH.sub.2), 2.48 (s, 3H, 30-CH.sub.3), 2.40 (t, J=7.5 Hz, 2H, 11-CH.sub.2), 2.17-2.25 (m, 1H, 37-CH), 2.07-2.15 (m, 1H, 37-CH), 1.99 (s, 3H, 45-CH.sub.3), 1.78-1.87 (m, 2H, 2-CH.sub.2), 1.71 (quin, J=7.3 Hz, 2H, 10-CH.sub.2), 1.46-1.56 (m, 2H, 3-CH.sub.2), 1.32-1.42 (m, 12H, (4-9)-CH.sub.2), 1.02 (s, 9H, 43-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.49H.sub.66N.sub.7O.sub.7S: 896.4744, found 896.4744.

##STR00056##

[0211] (2S,4R)-N-(2-((12-((4-((2-aminophenyl)carbamoyl)phenyl)amino)-12-oxododecyl)oxy)-4-(4-methylthiazol-5-yl)benzyl)-1-((S)-2-(1-fluorocyclopropane-1-carboxamido)-3,3-dimethylbutanoyl)-4-hydroxypyrrolidine-2-carboxamide (PROTAC36): Following general method H, Boc deprotection of 30b (24.2 mg, 0.022 mmol) was performed followed by purification by column chromatography (2-5% MeOH in DCM) to afford PROTAC36 (11.7 mg, 0.012 mmol, 57% yield) as a white solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 28-CH), 7.95 (d, J=8.7 Hz, 2H, 15-CH), 7.72 (d, J=8.7 Hz, 2H, 14-CH), 7.47 (d, J=7.7 Hz, 1H, 32-CH), 7.17 (dd, J=7.8, 1.3 Hz, 1H, 23-CH), 7.06 (app. td, J=7.8, 1.3 Hz, 1H, 21-CH), 6.96-7.02 (m, 2H, 25,31-CH), 6.90 (dd, J=7.8, 1.3 Hz, 1H, 20-CH), 6.76 (app. td, J=7.8, 1.3 Hz, 1H, 22-CH), 4.74 (d, J.sub.HF=0.8 Hz, 1H, 41-CH), 4.60-4.67 (m, 1H, 36-CH), 4.49-4.53 (m, 1H, 38-CH), 4.47 (d, J=16.0 Hz, 1H, 34-CH), 4.39 (d, J=16.0 Hz, 1H, 34-CH), 4.06 (t, J=6.3 Hz, 2H, 1-CH.sub.2), 3.82-3.88 (m, 1H, 39-CH), 3.76-3.81 (m, 1H, 39-CH), 2.48 (s, 3H, 30-CH.sub.3), 2.40 (t, J=7.5 Hz, 2H, 11-CH.sub.2), 2.19-2.27 (m, 1H, 37-CH), 2.09-2.16 (m, 1H, 37-CH), 1.78-1.89 (m, 2H, 2-CH.sub.2), 1.64-1.76 (m, 2H, 10-CH.sub.2), 1.48-1.57 (m, 2H, 3-CH.sub.2), 1.28-1.40 (m, 16H, (4-9)-CH.sub.2,46-CH.sub.2), 1.04 (s, 9H, 43-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.51H.sub.67FN.sub.7O.sub.7S: 940.4807, found 940.4781.

Synthesis of HDAC PROTACs Containing IAP Ligands

[0212] ##STR00057## ##STR00058##

[0213] Tert-butyl ((S)-1-(((S)-2-((2S,4S)-4-(12-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-12-oxododecanamido)-2-(((R)-1,2,3,4-tetrahydronaphthalen-1-yl)carbamoyl)pyrrolidin-1-yl)-1-cyclohexyl-2-oxoethyl)amino)-1-oxopropan-2-yl)(methyl)carbamate (32a): Following general method K, 32a was obtained from 26a (24.3 mg, 0.045 mmol) and A 410099.1 amine (24.5 mg, 0.038 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 32a (26.1 mg, 0.023 mmol, 60% yield) as a pale yellow solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.62H8.sub.9N80.sub.1: 1105.6702, found 1105.6704.

[0214] Tert-butyl ((S)-1-(((S)-2-((2S,4S)-4-(2-(2-(2-(2-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)ethoxy)ethoxy)acetamido)-2-(((R)-1,2,3,4-tetrahydronaphthalen-1-yl)carbamoyl)pyrrolidin-1-yl)-1-cyclohexyl-2-oxoethyl)amino)-1-oxopropan-2-yl)(methyl)carbamate (32b): Following general method K, 32b was obtained from 31 (24.0 mg, 0.045 mmol) and A 410099.1 amine (24.5 mg, 0.038 mmol). The crude product was purified by column chromatography (0-10% MeOH in DCM) to afford 32b (34.0 mg, 0.031 mmol, 81% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.58H8.sub.1N80.sub.13: 1097.5923, found 1097.5881.

##STR00059##

[0215] N.sup.1-(4-((2-aminophenyl)carbamoyl)phenyl)-N.sup.12-((3S,5S)-1-((S)-2-cyclohexyl-2-((S)-2-(methylamino) propanamido)acetyl)-5-(((R)-1,2,3,4-tetrahydronaphthalen-1-yl)carbamoyl)pyrrolidin-3-yl) dodecanediamide (PROTAC26): Following general method H, dual Boc deprotection of 32a (26.1 mg, 0.0227 mmol) was performed to afford PROTAC26 (21.0 mg, 0.0223 mmol, 98% yield) as a pale yellow solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 7.95 (d, J=8.7 Hz, 2H, 15-CH), 7.73 (d, J=8.7 Hz, 2H, 14-CH), 7.35-7.42 (m, 1H, 35-CH), 7.18 (dd, J=7.8, 1.2 Hz, 1H, 23-CH), 7.11-7.15 (m, 2H, 36,37-CH), 7.05-7.10 (m, 2H, 21,38-CH), 6.90 (dd, J=7.8, 1.2 Hz, 1H, 20-CH), 6.77 (app. td, J=7.8, 1.2 Hz, 1H, 22-CH), 5.02-5.09 (m, 1H, 29-CH), 4.41-4.53 (m, 3H, 24,26,40-CH), 4.16 (dd, J=10.3, 6.2 Hz, 1H, 27-CH), 3.57 (dd, J=10.3, 5.4 Hz, 1H, 27-CH), 3.13 (q, J=6.8 Hz, 1H, 48-CH), 2.72-2.84 (m, 2H, 32-CH.sub.2), 2.46-2.55 (m, 1H, 25-CH), 2.40 (t, J=7.4 Hz, 2H, 11-CH.sub.2), 2.29 (s, 3H, 50-CH.sub.3), 2.19 (t, J=7.5 Hz, 2H, 2-CH.sub.2), 1.67-1.96 (m, 13H, 10,30,31-CH.sub.2,25,41,(42-46)-CH), 1.57-1.64 (m, 2H, 3-CH.sub.2), 1.32-1.42 (m, 12H, (4-9)-CH.sub.2), 1.23-1.29 (m, 3H, (43-45)-CH), 1.20 (d, J=6.8 Hz, 3H, 49-CH.sub.3), 1.03-1.05 (m, 2H, 42,46-CH). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.52H.sub.73N.sub.8O.sub.6: 905.5653, found 905.5648.

##STR00060##

[0216] (2S,4S)-4-(2-(2-(2-(2-((4-((2-aminophenyl)carbamoyl)phenyl)amino)-2-oxoethoxy)ethoxy)ethoxy) acetamido)-1-((S)-2-cyclohexyl-2-((S)-2-(methylamino)propanamido)acetyl)-N-((R)-1,2,3,4-tetrahydronaphthalen-1-yl)pyrrolidine-2-carboxamide (PROTAC28): Following general method H, dual Boc deprotection of 32b (34.0 mg, 0.031 mmol) was performed to afford PROTAC28 (26.8 mg, 0.029 mmol, 95% yield) as a white solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 7.98 (d, J=8.7 Hz, 2H, 11-CH), 7.80 (d, J=8.7 Hz, 2H, 10-CH), 7.33-7.39 (m, 1H, 31-CH), 7.19 (dd, J=7.8, 1.3 Hz, 1H, 19-CH), 7.03-7.15 (m, 4H, 17,32,33,34-CH), 6.90 (dd, J=7.8, 1.3 Hz, 1H, 16-CH), 6.75 (app. td, J=7.8, 1.3 Hz, 1H, 18-CH), 5.00-5.08 (m, 1H, 25-CH), 4.58-4.65 (m, 1H, 20-CH), 4.46 (dd, J=8.9, 4.7 Hz, 1H, 22-CH), 4.43 (d, J=8.4 Hz, 1H, 36-CH), 4.08-4.18 (m, 3H, 7-CH.sub.2,23-CH), 4.01 (s, 2H, 2-CH.sub.2), 3.79-3.87 (m, 2H, PEG-CH.sub.2), 3.70-3.79 (m, 6H, PEG-CH.sub.2×3), 3.62-3.68 (m, 1H, 23-CH), 3.09 (q, J=6.8 Hz, 1H, 44-CH), 2.68-2.85 (m, 2H, 28-CH.sub.2), 2.44-2.53 (m, 1H, 21-CH.sub.2), 2.26 (s, 3H, 46-CH.sub.3), 1.62-1.98 (m, 11H, 26,27-CH.sub.2,21,37,(38-42)-CH), 1.17-1.27 (m, 3H, (39-41)-CH), 1.16 (d, J=6.9 Hz, 3H, 45-CH.sub.3), 0.98-1.13 (m, 2H, 38,42-CH). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.48H.sub.65N.sub.8O.sub.9: 897.4875, found 897.4860.

[0217] Tert-butyl ((S)-1-(((S)-2-((S)-2-(4-(3-((12-((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)phenyl)amino)-12-oxododecyl)oxy)benzoyl)thiazol-2-yl)pyrrolidin-1-yl)-1-cyclohexyl-2-oxoethyl)amino)-1-oxopropan-2-yl)(methyl)carbamate (33): Following general method I, 33 was obtained from tert-butyl ((S)-1-(((S)-1-cyclohexyl-2-((S)-2-(4-(3-hydroxybenzoyl)thiazol-2-yl)pyrrolidin-1-yl)-2-oxoethyl)amino)-1-oxopropan-2-yl)(methyl)carbamate (LCL16i phenol, 20.5 mg, 0.034 mmol) and 29 (20.0 mg, 0.034 mmol). The crude product was purified by column chromatography (1-8% MeOH in DCM) to afford 33 (14.7 mg, 0.013 mmol, 37% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.61H.sub.84N.sub.7O.sub.10S: 1106.6000, found 1106.5963.

##STR00061##

[0218] N-(2-aminophenyl)-4-(12-(3-(2-((S)-1-((S)-2-cyclohexyl-2-((S)-2-(methylamino)propanamido)acetyl) pyrrolidin-2-yl)thiazole-4-carbonyl)phenoxy)dodecanamido)benzamide (PROTAC37): Following general method H, dual Boc deprotection of 33 (14.7 mg, 0.013 mmol) was performed followed by purification by column chromatography (0-10% MeOH in DCM) to afford PROTAC37 (9.4 mg, 0.0103 mmol, 82% yield) as a white solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.32 (s, 1H, 32-CH), 7.95 (d, J=8.7 Hz, 2H, 15-CH), 7.65-7.76 (m, 4H, 14,27,29-CH), 7.42 (app. t, J=8.0 Hz, 1H, 26-CH), 7.15-7.22 (m, 2H, 23,25-CH), 7.07 (app. td, J=7.8, 1.3 Hz, 1H, 21-CH), 6.90 (dd, J=7.8, 1.3 Hz, 1H, 20-CH), 6.77 (app. td, J=7.8, 1.3 Hz, 1H, 22-CH), 5.48 (dd, J=7.8, 3.1 Hz, 1H, 34-CH), 4.52-4.60 (m, 1H, 39-CH), 4.04 (t, J=6.4 Hz, 2H, 1-CH.sub.2), 3.95-4.01 (m, 1H, 37-CH), 3.86-3.93 (m, 1H, 37-CH), 3.20 (q, J=6.8 Hz, 1H, 47-CH), 2.40 (t, J=7.5 Hz, 2H, 11-CH.sub.2), 2.29-2.37 (m, 4H, 35-CH, 49-CH.sub.3), 2.18-2.28 (m, 2H, 35,36-CH), 2.08-2.17 (m, 1H, 36-CH), 1.77-1.85 (m, 2H, 2-CH.sub.2), 1.54-1.77 (m, 8H, 10-CH.sub.2,40-CH,(41-45)-CH), 1.46-1.53 (m, 2H, 3-CH.sub.2), 1.32-1.43 (m, 12H, (4-9)-CH.sub.2), 1.24 (d, J=6.8 Hz, 3H, 48-CH.sub.3), 1.00-1.18 (m, 5H, (41-45)-CH). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.51H.sub.68N.sub.7O.sub.6S: 906.4952, found 906.4925.

Synthesis of HDAC PROTACs Containing a CRBN Ligand

[0219] ##STR00062##

[0220] 9-((tert-butoxycarbonyl)amino)nonanoic acid (35a): A solution of d-tert-butyldicarbonate (0.305 g, 140 mmol) in 1,4-di oxane/water (2:1, 2 mL) was added slowly to a solution of 34a (0.220 g, 1.27 mmol) and NaOH (0.051 g, 0.27 mmol) in 1,4-dioxane/water (2:1, 7 mL at 0° C., and then the mixture was stirred at room temperature for 64 hours. The reaction mixture was concentrated in vacuo to afford an off-yellow solid (0.391 g), then the basic residue redissolved in water (20 mL) and washed with EtOAc (2×20 mL). The aqueous phase was then acidified with 1 M HCl (ca. 2 mL) to pH 1 and extracted with EtOAc (3×20 ml). The organic phases were combined, dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo to afford 35a (0.260 g, 0.94 mmol, 74% yield) as a clear yellow tar (slowly crystallised). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.14H.sub.28NO.sub.4: 274.2018, found 274.2017.

[0221] 12-((Tert-butoxycarbonyl)amino)dodecanoic acid (35b): A solution of Boc.sub.2O (2.23 g, 10.22 mmol) in 1,4-dioxane/water (2:1, 1.0 mL) was added slowly to a solution of 34b (2.00 g, 9.29 mmol) and NaOH (0.37 g, 9.29 mmol) in 1,4-dioxane/water (2:1, 50 mL) at 0° C., and then the mixture was stirred at room temperature for 18 hours. The reaction mixture was concentrated in vacuo, then the basic residue redissolved in water (100 mL) and washed with EtOAc (2×50 mL). The aqueous phase was then acidified with 1 M HCl (ca. 15 mL) to pH 1 and extracted with EtOAc (3×100 mL). The organic phases were combined, dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo to afford 35b (2.41 g, 7.56 mmol, 81% yield) as a fluffy white solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.17H.sub.33NO.sub.4Na: 338.2307, found 338.2307.

[0222] Tert-butyl (2-(4-(9-((tert-butoxycarbonyl)amino)nonanamido)benzamido)phenyl)carbamate (36a): Following general method E, 36a was obtained from 35a (247.5 mg, 0.91 mmol) and 11a (250.0 mg, 0.76 mmol). The crude product was purified by column chromatography (0-80% EtOAc in hexane) to afford 36a (255.8 mg, 0.43 mmol, 57% yield). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.32H.sub.47N.sub.4O.sub.6: 583.3496, found 583.3492.

[0223] Tert-butyl (2-(4-(12-((tert-butoxycarbonyl)amino)dodecanamido)benzamido)phenyl)carbamate (36b):

[0224] Following general method E, 36b was obtained from 35b (318 mg, 1.01 mmol) and 11a (300 mg, 0.92 mmol).

[0225] The crude product was purified by column chromatography (50% EtOAc in hexane) to afford 36b (374 mg, 0.59 mmol, 65% yield) as a pale yellow crystalline solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.35H.sub.52N.sub.4O.sub.6Na: 647.3785, found 647.3792.

[0226] 4-(9-aminononanamido)-N-(2-aminophenyl)benzamide (37a): Following general method C, Boc deprotection of 36a (96.0 mg, 0.165 mmol) was performed to afford 37a (54.0 mg, 0.140 mmol, 85% yield) as a pale yellow solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.22H.sub.31N.sub.4O.sub.2: 383.2447, found 383.2440.

[0227] 4-(12-Aminododecanamido)-N-(2-aminophenyl)benzamide (37b): Following general method C, Boc deprotection of 36b (159 mg, 0.255 mmol) was performed to afford 37b (104 mg, 0.242 mmol, 95% yield) as a pale yellow solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.25H.sub.37N.sub.4O.sub.2: 425.2917, found 425.2918.

##STR00063##

[0228] N-(2-aminophenyl)-4-(9-(2-((2-(2,6-dioxopiperidin-3-yl)-1,3-dioxoisoindolin-4-yl)oxy)acetamido)nonanamido)benzamide (PROTAC5): Following general method J, PROTAC5 was obtained from CRBN acid (33.9 mg, 0.102 mmol) and 37a (39.0 mg, 0.102 mmol). The crude product was purified by column chromatography (5% MeOH in DCM) to afford PROTAC5 (22.5 mg, 0.032 mmol, 31% yield) as a pale yellow solid. .sup.1H NMR (400 MHz, Methanol-d4) δ.sub.H ppm 7.94 (d, J=8.7 Hz, 2H, 12-CH), 7.79 (dd, J=8.4, 7.3 Hz, 1H, 25-CH), 7.71 (d, J=8.7 Hz, 2H, 11-CH), 7.52 (dd, J=7-3, 0.5 Hz, 1H, 26-CH), 7.41 (dd, J=8.4, 0.5 Hz, 1H, 24-CH), 7.18 (app. dd, J=7.7, 1.4 Hz, 1H, 20-CH), 7.08 (app. td, J=7.7, 1.4 Hz, 1H, 18-CH), 6.90 (app. dd, J=7.7, 1.4 Hz, 1H, 17-CH), 6.77 (app. td, J=7.7, 1.4 Hz, 1H, 19-CH), 5.13 (dd, J=12.5, 5.5 Hz, 1H, 31-CH), 4.75 (s, 2H, 22-CH.sub.2), 3.29-3.33 (m, 2H, 1-CH.sub.2), 2.82-2.93 (m, 1H, 34-CH), 2.66-2.79 (m, 2H, 34-CH,35-CH), 2.39 (t, J=7.5 Hz, 2H, 8-CH.sub.2), 2.10-2.18 (m, 1H, 35-CH), 1.70 (quin, J=7.1 Hz, 2H, 7-CH.sub.2), 1.58 (quin, J=7.1 Hz, 2H, 2-CH.sub.2), 1.35-1.40 (m, 8H, (3-6)-CH.sub.2). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.37H.sub.41N.sub.6O.sub.8; 697.2986, found 697.2981.

##STR00064##

[0229] N-(2-aminophenyl)-4-(12-(2-((2-(2,6-dioxopiperidin-3-yl)-1,3-dioxoisoindolin-4-yl)oxy)acetamido) dodecanamido)benzamide (PROTAC2): Following general method J, PROTAC2 was obtained from CRBN acid (31.6 mg, 0.095 mmol) and 37b (40.4 mg, 0.095 mmol). The crude product was purified by column chromatography (5% MeOH in DCM) to afford PROTAC2 (25.4 mg, 0.033 mmol, 34% yield) as a pale yellow solid. .sup.1H NMR (400 MHz, DMSO-d.sub.6) δ.sub.H ppm 11.11 (br s, 1H, NH), 10.11 (s, 1H, NH), 9.54 (s, 1H, NH), 7.93 (d, J=8.8 Hz, 2H, 15-CH), 7.91 (s, 1H, NH), 7.81 (dd, J=8.4, 7.2 Hz, 1H, 28-CH), 7.70 (d, J=8.8 Hz, 2H, 14-CH), 7.50 (d, J=7.2 Hz, 1H, 29-CH), 7.39 (d, J=8.4 Hz, 1H, 27-CH), 7.15 (dd, J=7.7, 1.4 Hz, 1H, 23-CH), 6.96 (app. td, J=7.7, 1.4 Hz, 1H, 21-CH), 6.78 (dd, J=7.7, 1.4 Hz, 1H, 20-CH), 6.59 (app. td, J=7.7, 1.4 Hz, 1H, 22-CH), 5.12 (dd, J=12.9, 5.4 Hz, 1H, 34-CH), 4.87 (s, 2H, NH.sub.2), 4.76 (s, 2H, 25-CH.sub.2), 3.13 (q, J=6.5 Hz, 2H, 1-CH.sub.2), 2.85-2.95 (m, 1H, 37-CH), 2.53-2.63 (m, 2H, 37-CH,38-CH), 2.33 (t, J=7.4 Hz, 2H, 11—CH.sub.2), 2.00-2.07 (m, 1H, 38-CH), 1.59 (quin, J=7.0 Hz, 2H, 10-CH.sub.2), 1.39-1.47 (m, 2H, 2-CH.sub.2), 1.23-1.31 (m, 14H, (3-9)-CH.sub.2). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.40H.sub.47N.sub.6O.sub.8: 739.3455, found 739.3455.

Utilising Click Chemistry to Synthesize a HDAC PROTAC Containing a VHL Ligand

[0230] ##STR00065##

[0231] 4-({[(Prop-2-yn-1-yloxy)carbonyl]amino}methyl)benzoic acid (38): Propargyl alcohol (0.12 mL, 1.98 mmol) and carbonyldiimidazole (0.32 g, 1.98 mmol) were dissolved in THF (5 mL) and stirred at 10° C. for 1 h. 4-(Aminomethyl)benzoic acid (0.30 g, 1.98 mmol), DBU (0.29 mL, 1.98 mmol) and triethylamine (0.27 mL, 1.98 mmol) were suspended in THF (5 mL) and combined with the CDI-intermediate solution and the reaction stirred at room temperature for 16 h. The solvent was removed under reduced pressure, suspended in H.sub.2O (10 mL) and the solution was acidified with 1M HCl solution to pH 5. The resulting precipitate was collected by gravity filtration and air dried to provide 38 (0.35 g, 75% yield) as a white powder. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.12H.sub.12NO.sub.4: 234.0766, found 234.0764.

[0232] Tert-butyl N-{2-[4-({[(prop-2-yn-1-yloxy)carbonyl]amino}methyl)benzamido]phenyl} carbamate (39): 38 and HATU (0.49 g, 1.28 mmol) were dissolved in anhydrous DMF (5 mL) and stirred at room temperature for 1 h. Tert-butyl N-(2-aminophenyl)carbamate (0.18 g, 0.85 mmol) and diisopropylethylamine (0.30 mL, 1.71 mmol) were added and the reaction stirred at room temperature for 16 h. The solvent was removed under reduced pressure and suspended in EtOAc (20 mL). The organic solution was washed with sat. NaHCO.sub.3 (2×20 mL), brine (20 mL), the organic layers combined, dried over MgSO.sub.4, filtered and the solvent removed under reduced pressure. The crude oil was purified by flash chromatography on silica (Hexane:EtOAc 30:70-50:50 gradient) to provide 39 (0.28 g, 76% yield) as a pale pink oil. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.23H.sub.26N.sub.3O.sub.5: 424.1872, found 424.1871.

[0233] 8-(4-((((4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)benzyl)carbamoyl)oxy)methyl)-1H-1,2,3-triazol-1-yl)octanoic acid (40): 39 (0.13 g, 0.29 mmol), 8-azido-octanoic acid (0.05 g, 0.29 mmol) and CuI (0.01 g, 0.10 mmol) were suspended in degassed DMF:MeCN (5 mL, 2:1) under an inert atmosphere. 2,6-Lutidine (0.06 g, 0.52 mmol) was added and the reaction stirred at room temperature for 16 h. The solvent was removed under reduced pressure and suspended in EtOAc (10 mL), washed with sat. NaHCO.sub.3 (2×10 mL), brine (2×10 mL), the organic layers combined, dried over MgSO.sub.4, filtered and the solvent removed under reduced pressure. The crude oil was purified by flash chromatography on silica (3-5% MeOH:DCM solvent gradient) to provide 40 (0.08 g, 46%) as an off white solid. HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.31H.sub.40N.sub.6O.sub.7Na: 631.2856, found 631.2856.

[0234] (1-(8-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-8-oxooctyl)-1H-1,2,3-triazol-4-yl)methyl(4-((2-((tert-butoxycarbonyl)amino)phenyl)carbamoyl)benzyl)carbamate (41): Following general method G, 41 was obtained from 40 (0.075 g, 0.12 mmol) and VH_032 amine (0.05 g, 0.10 mmol). The crude product was purified by flash chromatography on silica (2-7% MeOH:DCM solvent gradient) to provide 41 as an off-white crystalline solid (0.08 g, 78%). HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.53H.sub.68N.sub.10O.sub.9SNa: 1043.4789, found 1043.4758.

##STR00066##

[0235] (1-(8-(((S)-1-((2S,4R)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-8-oxooctyl)-1H-1,2,3-triazol-4-yl)methyl(4-((2-amino phenyl)carbamoyl)benzyl)carbamate (PROTAC29): Following general method H, Boc deprotection of 41 (0.08 g, 0.08 mmol) was performed to afford PROTAC29 (0.06 g, 84%) as an off-white solid. .sup.1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.75 (s, 1H, 45-CH), 7.87 (s, 1H, 1-CH), 7.82 (m, 2H, 9-CH), 7.35-7.33 (m, 2H, 41-CH), 7.31-7.27 (m, 4H, 8-CH, 42-CH), 7.08-7.06 (m, 1H, 14-CH), 6.98-6.94 (m, 1H, 16-CH), 6.80-6.77 (m, 1H, 17-CH), 6.67-6.63 (m, 1H, 15-CH), 5.05 (s, 2H, 3-CH.sub.2), 4.51 (s, 1H, 29-CH), 4.47-4.39 (m, 2H, 36-CH, 39-CH), 4.38-4.36 (m, 1H, 34-CH), 4.28-4.19 (m, 3H, 20-CH.sub.2, 39-CH), 4.25 (s, 2H, 6-CH.sub.2), 3.79-3.76 (m, 1H, 33-CH), 3.69-3.65 (m, 1H, 33-CH), 2.35 (s, 3H, 47-CH.sub.3), 2.17-2.06 (m, 3H, 26-CH.sub.2, 35-CH), 1.99-1.92 (m, 1H, 35-CH), 1.80-1.73 (m, 2H, 21-CH.sub.2), 1.49-1.42 (m, 2H, 25-CH.sub.2), 1.23-1.14 (m, 6H, 22-CH.sub.2, 23-CH.sub.2, 24-CH.sub.2). 0.91 (s, 9H, 31-CH.sub.3). HRMS (ESI) m/z: [M+Na].sup.+ calculated for C.sub.48H.sub.60N.sub.10O.sub.7SNa: 943.4265, found 943.4246.

Synthesis of PROTAC4 Negative Control using an Inactive Isomer of the VHL Ligand

##STR00067##

[0236] Tert-butyl (2-(4-(12-(((S)-1-((2S,4S)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)amino)-12-oxododecanamido)benzamido)phenyl)carbamate (27a*): To a solution of 26a (51.4 mg, 0.095 mmol) in dry DMF (1 mL) at 0° C., DIPEA (0.04 mL, 0.238 mmol) and HATU (39.3 mg, 0.103 mmol) were added. The reaction mixture was stirred for 15 minutes, after which a solution of (2S,4S)-1-[(2S)-2-Amino-3,3-dimethyl-butanoyl]-4-hydroxy-N-[[4-(4-methylthiazol-5-yl)phenyl]methyl]pyrrolidine-2-carboxamide dihydrochloride (VH_032* amine, 40.0 mg, 0.079 mmol) in DMF (1 mL) was added slowly and the resultant solution stirred at room temperature for 16 hours. The reaction mixture was diluted in EtOAc (10 mL), then washed with sat. NaHCO.sub.3 (2×5 mL) and sat. NaCl (2×5 mL). The organic layer was dried over MgSO.sub.4, filtered and concentrated in vacuo to afford a dark yellow tar (104 mg). The crude product was purified by column chromatography (0-5% MeOH in DCM) to afford 27a* (50.8 mg, 0.053 mmol, 67% yield) as a white solid. HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.52H.sub.70N.sub.7O.sub.8S: 952.5007, found 952.4999.

##STR00068##

[0237] N1-(4-((2-aminophenyl)carbamoyl)phenyl)-N12-((S)-1-((2S,4S)-4-hydroxy-2-((4-(4-methylthiazol-5-yl)benzyl)carbamoyl)pyrrolidin-1-yl)-3,3-dimethyl-1-oxobutan-2-yl)dodecanediamide (NC-PROTAC4): Following general method H, Boc deprotection of 27a* (29.0 mg, 0.030 mmol) was performed to afford NC-PROTAC4 (25.6 mg, 0.029 mmol, 98% yield) as a pale yellow solid. Prior to biological evaluation the product was further purified by semi-preparative HPLC (5-95% MeCN in H.sub.2O, 260 nm, 45 min gradient). 1H NMR (400 MHz, Methanol-d.sub.4) δ.sub.H ppm 8.86 (s, 1H, 39-CH) 7.95 (d, J=8.7 Hz, 2H, 15-CH) 7.72 (d, J=8.7 Hz, 2H, 14-CH) 7.44 (d, J=8.5 Hz, 2H, 36-CH) 7.40 (d, J=8.5 Hz, 2H, 35-CH) 7.18 (dd, J=7.8, 1.3 Hz, 1H, 23-CH) 7.07 (app. td, J=7.8, 1.3 Hz, 1H, 21-CH) 6.90 (dd, J=7.8, 1.3 Hz, 1H, 20-CH) 6.76 (app. td, J=7.8, 1.3 Hz, 1H, 22-CH), 4.47-4.58 (m, 3H, 24-CH,31-CH,33-CH) 4.32-4.40 (m, 2H, 29-CH,33-CH) 4.03 (dd, J=10.5, 5.1 Hz, 1H, 28-CH) 3.69 (dd, J=10.5, 3.5 Hz, 1H, 28-CH) 2.47 (s, 3H, 41-CH.sub.3) 2.42-2.45 (m, 1H, 30-CH) 2.40 (t, J=7.4 Hz, 2H, 11-CH.sub.2) 2.18-2.32 (m, 2H, 2-CH.sub.2) 1.97 (dt, J=13.3, 4.3 Hz, 1H, 30-CH) 1.70 (quin, J=7.4 Hz, 2H, 10-CH.sub.2) 1.53-1.63 (m, 2H, 3-CH.sub.2) 1.33-1.39 (m, 4H, 4-CH.sub.2,9-CH.sub.2) 1.29-1.33 (m, 8H, (5-8)-CH.sub.2) 1.03 (s, 9H, 26-CH.sub.3). HRMS (ESI) m/z: [M+H].sup.+ calculated for C.sub.47H.sub.62N.sub.7O.sub.6S: 852.4482, found 852.4483.

In vitro HDAC Assay with CoREST Complex

[0238] Inhibition tests against LSD1-HDAC-CoREST complex were performed using a two-enzyme fluorescence-based HDAC assay. The inhibitor/PROTACs were dissolved at 50 mM in DMSO, then 1:2 serial dilutions performed using HDAC assay buffer (50 mM Tris pH 7.5, 150 mM NaCl) to afford range of concentrations. 10 uL of these solutions were added to individual wells, followed by 20 μL of HDAC complex dissolved in HDAC assay buffer (18 nM) and 20 μL of the substrate Boc-(Ac)Lys-AMC dissolved in HDAC assay buffer.

[0239] The assays were performed in black 96-well plates with a reaction volume of 50 μL per well. All determinations were performed in triplicate. Control wells containing no inhibitor were used to determine when inhibition had ceased. After an incubation of 20 minutes at 37° C. and 150 rpm, deacetylation was stopped by the addition of 50 μL of a developing solution containing trypsin (50 mM Tris pH 7.5, 100 mM NaCl, 10 mg/mL trypsin). Fluorescence intensity was measured with a plate reader (PerkinElmer, 2030 multilabel reader, VICTOR X5, λ.sub.ex 335 nm, λ.sub.em 460 nm). HDAC Activity was calculated by subtracting the average blank fluorescence from the well fluorescence. Graphpad Prism software was utilised to determine IC.sub.50 values.

Cell Lines and Materials

[0240] E14 wild type (WT) mouse embryonic stem (mES) cells were maintained on gelatinised plates in standard mES media consisting of Knockout Dulbecco's Modified Eagle Medium (KO DMEM) (GIBCO, 10829-018) supplemented with 15% Fetal Bovine Serum (FBS) (Sigma, F9665), 1× glutamine/penicillin/streptomycin (GIBCO, 10378-016), 100 μM β-mercaptoethanol (Sigma) and Leukaemia Inhibitory Factor (synthesised in house). HCT116 human colon carcinoma cells were grown in Dulbecco's Modified Eagle Medium (DMEM) (GIBCO, 41965-039) supplemented with 10% Fetal Bovine Serum (FBS) (Sigma) and 1× glutamine/penicillin/streptomycin (GIBCO, 10378-016). Both cell lines were incubated at 37° C. with 5% CO.sub.2. Cells were treated with PROTACs (0.01-40 μM) alongside HDAC inhibitors CI-994 (10/40 μM) and Panobinostat (30 nM) as controls.

Western Blotting

[0241] HCT116 or mES cells were treated 24 hours after seeding. 24 hours post treatment, cells were harvested, lysed in lysis buffer (50 mM Tris-HCl, 150 mM NaCl, 0.5% NP-40, 0.5% Triton X-100) with protease inhibitor (Sigma, P8340), then incubated on ice for 30 minutes, before being centrifuged (18,000 ref, 15 minutes, 4° C.). The supernatant was collected, and protein concentrations quantified via Bradford Assay using Protein Assay Dye Reagent Concentrate (BIO-RAD). For histone extraction, an equal volume of 0.4 N H.sub.2SO.sub.4 was added to the pellets and the extracts placed at 4° C. overnight. Following overnight incubation, the tubes were centrifuged (18,000 ref, 15 minutes, 4° C.) and then the supernatant (histone extract) collected.

[0242] Western blots were run on NuPAGE™ 4-12% Bis-Tris gels with 20-30 μg of protein or 10 μL of acid-extracted histone loaded per lane, using NuPAGE™ LDS Sample Buffer (4×). PageRuler™ Plus Prestained Ladder was used for size standards. After gel electrophoresis at 140V for 75-90 minutes the separated proteins were transferred onto nitrocellulose membrane at 30V for 60 minutes. The membranes were probed with primary antibodies (listed below) for 60-90 minutes. Blots were developed with complimentary IRDye conjugated secondary antibodies and the bands visualised using the Odyssey Infrared Imaging System. Image processing and band intensity quantification was performed using Image Studio Lite.

Antibody Information

Primary Antibodies;

[0243] α-tubulin—Sigma, t5168 (1:10,000 dilution) [0244] HDAC1—Abcam, 109411 (1:2,000 dilution) [0245] HDAC2—Merck Millipore, 05-814 (1:2,000 dilution) [0246] HDAC3—Abcam, 32369 (1:2,000 dilution) [0247] H3—Merck Millipore, 05-499 (1:1,000 dilution) [0248] H3K9Ac—Upstate, 06-942 (1:1,000 dilution) [0249] H3K27Ac—Merck Millipore, 07-360 (1:1,000 dilution) [0250] H3K56Ac—Active Motif, 39281 (1:1,000 dilution)

Secondary Antibodies;

[0251] IRDye® 680LT—LI-COR Biosciences, 926-68023 (1:10,000 dilution) [0252] IRDye® 800CW—LI-COR Biosciences, 926-32210 (1:10,000 dilution)

Cell Viability Assay

[0253] To analyse cell death, cells were treated with DMSO, CI-994 (40 M), or PROTAC 4 (1-40 μM) 24 hours after seeding. 24 hours post treatment, cells were harvested and fixed with 70% (vol/vol) ethanol at −20° C. overnight. Cells were washed in PBS prior to incubation with 50 μg of propidium iodide and RNase A (10 μg/mL) for 30 min at room temperature in the dark. Samples were analysed using the BD FACSCanto II flow cytometer (BD Biosciences) in the PE A channel with BD FACSDiva software.