CONJUGATES OF-ELECTRON-PAIR-DONATING HETEROAROMATIC NITROGEN-COMPRISING COMPOUNDS

Abstract

The present invention relates to conjugates of π-electron-pair-donating heteroaromatic nitrogen-comprising drugs and pharmaceutically acceptable salts thereof, pharmaceutical compositions comprising said conjugates and the use of said conjugates as medicaments.

Claims

1. A conjugate or a pharmaceutically acceptable salt thereof comprising at least one moiety -D conjugated via at least one moiety -L.sup.1-L.sup.2- to at least one moiety Z, wherein a moiety -L.sup.1- is conjugated to a π-electron-pair-donating heteroaromatic N of a moiety -D and wherein the linkage between -D and -L.sup.1- is reversible and wherein a moiety -L.sup.2- is conjugated to Z, wherein each -D is independently a π-electron-pair-donating heteroaromatic N-comprising moiety of a drug D-H; each -L.sup.2- is independently a single bond or a spacer moiety; each Z is independently a polymeric moiety or a C.sub.8-24 alkyl; each -L.sup.1- is independently a linker moiety of formula (I): ##STR00124## wherein the dashed line indicates the attachment to the π-electron-pair-donating heteroaromatic N of -D; n is an integer selected from the group consisting of 0, 1, 2, 3 and 4; ═X.sup.1 is selected from the group consisting of ═O, ═S and ═N(R.sup.4); —X.sup.2— is selected from the group consisting of —O—, —S—, —N(R.sup.5)— and —C(R.sup.6)(R.sup.6a)—; —X.sup.3— is selected from the group consisting of ##STR00125##  C(R.sup.10)(R.sup.10a)—, —C(R.sup.11)(R.sup.11a)—C(R.sup.12)(R.sup.12a)—, —O— and —C(O)—; —R.sup.1, —R.sup.1a, —R.sup.6, —R.sup.6a, —R.sup.10, —R.sup.10a, —R.sup.11, —R.sup.11a, —R.sup.12, —R.sup.12a and each of —R.sup.2 and —R.sup.2a are independently selected from the group consisting of —H, —C(O)OH, halogen, —CN, —OH, C.sub.1-6 alkyl, C.sub.2-6 alkenyl and C.sub.2-6 alkynyl; wherein C.sub.1-6 alkyl, C.sub.2-6 alkenyl and C.sub.2-6 alkynyl are optionally substituted with one or more —R.sup.13, which are the same or different; and wherein C.sub.1-6 alkyl, C.sub.2-6 alkenyl and C.sub.2-6 alkynyl are optionally interrupted by one or more groups selected from the group consisting of -T-, —C(O)O—, —O—, —C(O)—, —C(O)N(R.sup.14)—, —S(O).sub.2N(R.sup.14)—, —S(O)N(R.sup.14)—, —S(O).sub.2—, —S(O)—, —N(R.sup.14)S(O).sub.2N(R.sup.14a)—, —S—, —N(R.sup.14), —OC(OR.sup.14)(R.sup.14a)—, —N(R.sup.14)C(O)N(R.sup.14a)— and —OC(O)N(R.sup.14)—; —R.sup.3, —R.sup.4, —R.sup.5, —R.sup.7, —R.sup.8 and —R.sup.9 are independently selected from the group consisting of —H, -T, —CN, C.sub.1-6 alkyl, C.sub.2-6 alkenyl and C.sub.2-6 alkynyl; wherein C.sub.1-6 alkyl, C.sub.2-6 alkenyl and C.sub.2-6 alkynyl are optionally substituted with one or more —R.sup.13, which are the same or different; and wherein C.sub.1-6 alkyl, C.sub.2-6 alkenyl and C.sub.2-6 alkynyl are optionally interrupted by one or more groups selected from the group consisting of -T-, —C(O)O—, —O—, —C(O)—, —C(O)N(R.sup.14)—, —S(O).sub.2N(R.sup.14)—, —S(O)N(R.sup.14)—, —S(O).sub.2—, —S(O)—, —N(R.sup.14)S(O).sub.2N(R.sup.14a)—, —S—, —N(R.sup.14)—, —OC(OR.sup.14)(R.sup.14a)—, —N(R.sup.14)C(O)N(R.sup.14a)— and —OC(O)N(R.sup.14)—; each T is independently selected from the group consisting of phenyl, naphthyl, indenyl, indanyl, tetralinyl, C.sub.3-10 cycloalkyl, 3- to 10-membered heterocyclyl and 8- to 11-membered heterobicyclyl; wherein each T is independently optionally substituted with one or more —R.sup.13, which are the same or different; wherein —R.sup.13 is selected from the group consisting of —H, —NO.sub.2, —OCH.sub.3, —CN, —N(R.sup.14)(R.sup.14a), —OH, —C(O)OH and C.sub.1-6 alkyl; wherein C.sub.1-6 alkyl is optionally substituted with one or more halogen, which are the same or different; wherein —R.sup.14 and —R.sup.14a are independently selected from the group consisting of —H and C.sub.1-6 alkyl; wherein C.sub.1-6 alkyl is optionally substituted with one or more halogen, which are the same or different; optionally, one or more of the pairs —R.sup.1/—R.sup.1a, —R.sup.2/—R.sup.2a, two adjacent —R.sup.2, —R.sup.6/—R.sup.6a, —R.sup.10/—R.sup.10a, —R.sup.11/—R.sup.11a, —R.sup.12/—R.sup.12a and —R.sup.3/—R.sup.9 are joined together with the atom to which they are attached to form a C.sub.3-10 cycloalkyl, 3- to 10-membered heterocyclyl or an 8- to 11-membered heterobicyclyl; optionally, one or more of the pairs —R.sup.1/—R.sup.2, —R.sup.1/—R.sup.5, —R.sup.1/—R.sup.6, —R.sup.1/—R.sup.9, —R.sup.1/—R.sup.10, —R.sup.2/—R.sup.5, —R.sup.3/—R.sup.6a, —R.sup.4/—R.sup.5, —R.sup.4/—R.sup.6, —R.sup.5/—R.sup.10, —R.sup.6/—R.sup.10 and —R.sup.11/—R.sup.12 are joined together with the atoms to which they are attached to form a ring -A-; wherein -A- is selected from the group consisting of phenyl, naphthyl, indenyl, indanyl, tetralinyl, C.sub.3-10 cycloalkyl, 3- to 10-membered heterocyclyl and 8- to 11-membered heterobicyclyl; optionally, —R.sup.1 and an adjacent —R.sup.2 form a carbon-carbon double bond provided that n is selected from the group consisting of 1, 2, 3 and 4; optionally, two adjacent —R.sup.2 form a carbon-carbon double bond provided that n is selected from the group consisting of 2, 3 and 4; provided that if —X.sup.2— is —N(R.sup.5)—, —X.sup.3— is selected from the group consisting of ##STR00126##  and the distance between the nitrogen atom marked with an asterisk and the carbon atom marked with an asterisk in formula (I) is 5, 6 or 7 atoms and if present the carbon-carbon double bond formed between —R.sup.1 and —R.sup.2 or two adjacent —R.sup.2 is in a cis configuration; and each -L.sup.1- is substituted with -L.sup.2- and optionally further substituted.

2. The conjugate or pharmaceutically acceptable salt thereof of claim 1, wherein -D is selected from the group consisting of small molecule, medium size, peptide and protein drug moieties.

3. The conjugate or pharmaceutically acceptable salt thereof of claim 1 or 2, wherein -D is a small molecule drug moiety.

4. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 3, wherein Z is a polymeric moiety.

5. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 4, wherein Z is a water-insoluble polymeric moiety.

6. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 5, wherein Z is a water-insoluble polymeric moiety comprising a polymer selected from the group consisting of 2-methacryloyl-oxyethyl phosphoyl cholins, poly(acrylic acids), poly(acrylates), poly(acrylamides), poly(alkyloxy) polymers, poly(amides), poly(amidoamines), poly(amino acids), poly(anhydrides), poly(aspartamides), poly(butyric acids), poly(glycolic acids), polybutylene terephthalates, poly(caprolactones), poly(carbonates), poly(cyanoacrylates), poly(dimethylacrylamides), poly(esters), poly(ethylenes), poly(ethyleneglycols), poly(ethylene oxides), poly(ethyl phosphates), poly(ethyloxazolines), poly(glycolic acids), poly(hydroxyethyl acrylates), poly(hydroxyethyl-oxazolines), poly(hydroxymethacrylates), poly(hydroxypropylmethacrylamides), poly(hydroxypropyl methacrylates), poly(hydroxypropyloxazolines), poly(iminocarbonates), poly(lactic acids), poly(lactic-co-glycolic acids), poly(methacrylamides), poly(methacrylates), poly(methyloxazolines), poly(organophosphazenes), poly(ortho esters), poly(oxazolines), poly(propylene glycols), poly(siloxanes), poly(urethanes), poly(vinyl alcohols), poly(vinyl amines), poly(vinylmethylethers), poly(vinylpyrrolidones), silicones, celluloses, carbomethyl celluloses, hydroxypropyl methylcelluloses, chitins, chitosans, dextrans, dextrins, gelatins, hyaluronic acids and derivatives, functionalized hyaluronic acids, mannans, pectins, rhamnogalacturonans, starches, hydroxyalkyl starches, hydroxyethyl starches and other carbohydrate-based polymers, xylans, and copolymers thereof.

7. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 6, wherein Z is a hydrogel.

8. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 7, wherein Z is a PEG-based or hyaluronic-acid based hydrogel.

9. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 8, wherein Z is a PEG-based hydrogel.

10. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 8, wherein Z is a hyaluronic-acid based hydrogel.

11. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 4, wherein Z is a water-soluble polymeric moiety.

12. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 11, wherein ═X.sup.1 is ═O and —X.sup.2— is —O—.

13. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 11, wherein ═X.sup.1 is ═O and —X.sup.2— is —N(R.sup.5)—.

14. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 13, wherein -L.sup.2- is a spacer moiety.

15. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 14, wherein -L.sup.2- has a molecular weight in the range of from 14 g/mol to 750 g/mol.

16. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 15, wherein -L.sup.2- is a spacer moiety selected from the group consisting of -T′-, —C(O)O—, —O—, —C(O)—, —C(O)N(R.sup.y1)—, —S(O).sub.2N(R.sup.y1)—, —S(O)N(R.sup.y1)—, —S(O).sub.2—, —S(O)—, —N(R.sup.y1)S(O).sub.2N(R.sup.y1a)—, —S—, —N(R.sup.y1)—, —OC(OR.sup.y1)(R.sup.y1a)—, —N(R.sup.y1)C(O)N(R.sup.y1a)—, —OC(O)N(R.sup.y1)—, C.sub.1-50 alkyl, C.sub.2-50 alkenyl, and C.sub.2-50 alkynyl; wherein -T′-, C.sub.1-50 alkyl, C.sub.2-50 alkenyl and C.sub.2-50 alkynyl are optionally substituted with one or more —R.sup.y2, which are the same or different and wherein C.sub.1-50 alkyl, C.sub.2-50 alkenyl, and C.sub.2-50 alkynyl are optionally interrupted by one or more groups selected from the group consisting of -T′-, —C(O)O—, —O—, —C(O)—, —C(O)N(R.sup.y3)—, —S(O).sub.2N(R.sup.y3)—, —S(O)N(R.sup.y3)—, —S(O).sub.2—, —S(O)—, —N(R.sup.y3)S(O).sub.2N(R.sup.y3a)—, —S—, —N(R.sup.y3)—, —OC(OR.sup.y3)(R.sup.y3a)—, —N(R.sup.y3)C(O)N(R.sup.y3a)— and —OC(O)N(R.sup.y3)—; wherein —R.sup.y1 and —R.sup.y1a are independently selected from the group consisting of —H, -T′, C.sub.1-50 alkyl, C.sub.2-50 alkenyl and C.sub.2-50 alkynyl; wherein -T′, C.sub.1-50 alkyl, C.sub.2-50 alkenyl, and C.sub.2-50 alkynyl are optionally substituted with one or more —R.sup.y2, which are the same or different, and wherein C.sub.1-50 alkyl, C.sub.2-50 alkenyl and C.sub.2-50 alkynyl are optionally interrupted by one or more groups selected from the group consisting of -T′-, —C(O)O—, —O—, —C(O)—, —C(O)N(R.sup.y4)—, —S(O).sub.2N(R.sup.y4)—, —S(O)N(R.sup.y4)—, —S(O).sub.2—, —S(O)—, —N(R.sup.y4)S(O).sub.2N(R.sup.y4a)—, —S—, —N(R.sup.y4)—, —OC(OR.sup.y4)(R.sup.y4a)—, —N(R.sup.y4)C(O)N(R.sup.y4a)—, and —OC(O)N(R.sup.y4)—; each T′ is independently selected from the group consisting of phenyl, naphthyl, indenyl, indanyl, tetralinyl, C.sub.3-10 cycloalkyl, 3- to 10-membered heterocyclyl, 8- to 11-membered heterobicyclyl, 8- to 30-membered carbopolycyclyl and 8- to 30-membered heteropolycyclyl; wherein each T′ is independently optionally substituted with one or more —R.sup.y2, which are the same or different; each —R.sup.y2 is independently selected from the group consisting of halogen, —CN, oxo (═O), —COOR.sup.y5, —OR.sup.y5, —C(O)R.sup.y5, —C(O)N(R.sup.y5R.sup.y5a), —S(O).sub.2N(R.sup.y5R.sup.y5a), —S(O)N(R.sup.y5R.sup.y5a), —S(O).sub.2R.sup.y5, —S(O)R.sup.y5, —N(R.sup.y5)S(O).sub.2N(R.sup.y5aR.sup.y5b), —SR.sup.y5, —N(R.sup.y5R.sup.y5a), —NO.sub.2, —OC(O)R.sup.y5, —N(R.sup.y5)C(O)R.sup.y5a, —N(R.sup.y5)S(O).sub.2R.sup.y5a, —N(R.sup.y5)S(O)R.sup.y5a, —N(R.sup.y5)C(O)OR.sup.y5a, —N(R.sup.y5)C(O)N(R.sup.y5aR.sup.y5b), —OC(O)N(R.sup.y5R.sup.y5a), and C.sub.1-6 alkyl; wherein C.sub.1-6 alkyl is optionally substituted with one or more halogen, which are the same or different; and each —R.sup.y3, —R.sup.y3a, —R.sup.y4, —R.sup.y4a, —R.sup.y5, —R.sup.y5a and —R.sup.y5b is independently selected from the group consisting of —H and C.sub.1-6 alkyl; wherein C.sub.1-6 alkyl is optionally substituted with one or more halogen, which are the same or different.

17. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 16, wherein one hydrogen given by —R.sup.3 is replaced by -L.sup.2-.

18. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 17, wherein the linkage between Z and -L.sup.2- is stable.

19. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 11 and 13 to 18, wherein -L.sup.1- is of formula (Ix): ##STR00127## wherein the dashed line indicates the attachment to the π-electron-pair-donating heteroaromatic N of -D; ═X.sup.1, —R.sup.1, —R.sup.1a, —R.sup.2, —R.sup.2a, —R.sup.3, —R.sup.5 and n are used as defined in claim 1; optionally, one or more of the pairs —R.sup.1/—R.sup.1a, —R.sup.2/—R.sup.2a, two adjacent —R.sup.2 are joined together with the atom to which they are attached to form a C.sub.3-10 cycloalkyl, 3- to 10-membered heterocyclyl or an 8- to 11-membered heterobicyclyl; optionally, one or more of the pairs —R.sup.1/—R.sup.2, —R.sup.1/—R.sup.5, —R.sup.2/—R.sup.5 and —R.sup.4/—R.sup.5 are joined together with the atoms to which they are attached to form a ring -A-; wherein -A- is selected from the group consisting of phenyl, naphthyl, indenyl, indanyl, tetralinyl, C.sub.3-10 cycloalkyl, 3- to 10-membered heterocyclyl and 8- to 11-membered heterobicyclyl; optionally, —R.sup.1 and an adjacent —R.sup.2 form a carbon-carbon double bond provided that n is selected from the group consisting of 1, 2, 3 and 4; optionally, two adjacent —R.sup.2 form a carbon-carbon double bond provided that n is selected from the group consisting of 2, 3 and 4; and wherein the distance between the nitrogen atom marked with an asterisk and the carbon atom marked with an asterisk in formula (Ix) is 5, 6 or 7 atoms and if present the carbon-carbon double bond formed between —R.sup.1 and —R.sup.2 or two adjacent —R.sup.2 is in a cis configuration.

20. The conjugate or pharmaceutically acceptable salt thereof of claim 19, wherein —R.sup.5 of formula (Ix) is methyl.

21. The conjugate or pharmaceutically acceptable salt thereof of claim 19 or 20, wherein —R.sup.1 and —R.sup.1a of formula (Ix) are both —H.

22. A pharmaceutical composition comprising the conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 21.

23. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 21 or the pharmaceutical composition of claim 22 for use as a medicament.

24. The conjugate or pharmaceutically acceptable salt thereof of any one of claims 1 to 21 or the pharmaceutical composition of claim 22 for use in a method of treating a disease that can be treated with D-H.

25. A method of preventing a disease or treating a patient suffering from a disease that can be prevented or treated with D-H, comprising administering an effective amount of the conjugate or the pharmaceutically acceptable salt thereof of any one of claims 1 to 21 or the pharmaceutical composition of claim 22 to the patient.

Description

EXAMPLES

Materials and Methods

[0356] All materials were commercially available except where stated otherwise.

Amino Hydrogels

[0357] PEG based amino hydrogels were synthesized as described in example 3 of WO2011/012715A1 using different crosslinkers and crosslinking degrees to give different levels of amine content. All crosslinkers were based on 2 kDa PEG and were synthesized as described in example 2 of WO2011/012715A1 using adipic acid (C6), suberic acid (C8), or azelaic acid (C9). The choice of crosslinker is in brackets and the hydrogels were characterized by their free amine content: HG-1: 0.309 mmol/g (C6), HG-2: 0.300 mmol/g (C6), HG-3: 0.134 mmol/g (C6); HG-4: 0.668 mmol/g (C9); HG-5: 0.303 mmol/g (C6); HG-6: 0.668 mmol/g (C9); HG-7: 0.331 mmol/g (C6); HG-8: 0.686 mmol/g (C9); HG-9: 0.393 mmol/g; (C9): HG-10: 0.474 mmol/g (C8); HG-16: 0.483 mmol/g (C9)

[0358] The following hydrogels were prepared by modification of amine hydrogels with lysine as described in example 5 of WO2011/042450A1, and were characterised by their free amine content:

HG-11: 0564 mmol/g (from HG-5); HG-12: 0.614 mmol/g (from HG-7), HG-13: 0.691 mmol/g (from HG-9), HG-14: 0.934 mmol/g (from HG-10). HG-15: 0.621 mmol/g (from HG-7); HG-17: 0.864 mmol/g (from HG-16)

Reactions

[0359] Reactions were performed with dry solvents (CH.sub.2Cl.sub.2, DMF, THF) stored over molecular sieves purchased from Sigma-Aldrich Chemie GmbH, Munich, Germany. Generally, reactions were stirred at room temperature and monitored by LCMS.

Solid Phase Synthesis

[0360] Solid phase synthesis was performed in syringe reactors with frit. A standard Fmoc protocol was used. 2-Chlorotrityl chloride resin (100-200 mesh), 1% DVB (Merck, Darmstadt, Germany) was loaded with the first amino acid using DIPEA in DCM. Fmoc deprotection was performed using 2:2:96 piperidine/DBU/DMF. Coupling of the next amino acid was performed using PyBOP/DIPEA or HATU/DIPEA in DMF. Cleavage from the resin was performed using HFIP or TFA/TES/water/DCM 48:2:2:48. Products were concentrated in vacuo.

RP-HPLC Purification

[0361] Preparative RP-HPLC purifications were performed with a Waters 600 controller with a 2487 Dual Absorbance Detector or an Agilent Infinity 1260 preparative system using a Waters XBridge BEH300 Prep C18 10 μm, 150×30 mm column as stationary phase. Products were detected at 215 nm, 320 nm or 360 nm. Linear gradients of solvent system A (water containing 0.1% TFA v/v) and solvent system B (acetonitrile containing 0.1% TFA v/v) were used. HPLC fractions containing product were pooled and lyophilized if not stated otherwise.

Flash Chromatography

[0362] Flash chromatography purifications were performed on an Isolera One system or an Isolera Four system from Biotage AB, Sweden, using Biotage KP-Sil silica cartridges. Products were detected at 254 nm, 280 nm, or 360 nm.

RP-LPLC Purification

[0363] Low pressure RP chromatography purifications were performed on an Isolera One system or an Isolera Four system from Biotage AB, Sweden, using Biotage SNAP C18 cartridges. Products were detected at 215 nm and 360 nm. Linear gradients of solvent system A (water containing 0.1% TFA v/v) and solvent system B (acetonitrile containing 0.1% TFA v/v). LPLC fractions containing product were pooled and lyophilized if not stated otherwise.

[0364] UPLC-MS Analysis

Analytical ultra-performance LC (UPLC)-MS was performed on a Waters Acquity system or an Agilent 1290 Infinity II equipped with a Waters BEH300 C18 column (2.1×50 mm, 1.7 μm particle size or 2.1×100 mm, 1.7 μm particle size); solvent A: water containing 0.04% TFA (v/v), solvent B: acetonitrile containing 0.05% TFA (v/v) coupled to a Waters Micromass ZQ or coupled to an Agilent Single Quad MS system.
Drug Moiety Content Determination from Hydrogels

[0365] Drug moiety contents of hydrogels were determined by total release of the drug after basic incubation and LCMS quantification (UV based).

Example 1: Synthesis of Indazole Conjugate 1e

[0366] Linker reagent 1e was synthesized according to the following scheme:

##STR00053##

[0367] To a solution of N-Methyl-N-boc-ethylenediamine (2 g, 11.48 mmol) and NaCNBH.sub.3 (819 mg, 12.63 mmol) in MeOH (20 mL) was added 2,4,6-trimethoxybenzaldehyde (2.08 mg, 10.61 mmol) portion-wise. The mixture was stirred at RT for 90 min, acidified with 3 M HCl (4 mL) and stirred further 15 min. The reaction mixture was added to saturated NaHCO.sub.3 solution (200 mL) and extracted 5× with CH.sub.2Cl.sub.2. The combined organic phases were dried over Na.sub.2SO.sub.4 and the solvents were evaporated in vacuo. The resulting N-Methyl-N-boc-N′-tmob-ethylenediamine 1a was dried in high vacuum and used in the next reaction step without further purification.

[0368] Yield: 3.76 g (11.48 mmol, 89% purity, 1a: double Tmob protected product=8:1)

[0369] MS: m/z 355.22=[M+H].sup.+, (calculated=354.21).

[0370] To a solution of 1a (2 g, 5.65 mmol) in CH.sub.2Cl.sub.2 (24 ml) COMU (4.84 g, 11.3 mmol), N-Fmoc-N-Me-Asp(OBn)-OH (2.08 g, 4.52 mmol) and collidine (2.65 mL, 20.34 mmol) were added. The reaction mixture was stirred for 3 h at RT, diluted with CH.sub.2Cl.sub.2 (250 mL) and washed 3× with 0.1 M H.sub.2SO.sub.4 (100 mL) and 3× with brine (100 mL). The aqueous phases were re-extracted with CH.sub.2Cl.sub.2 (100 mL). The combined organic phases were dried over Na.sub.2SO.sub.4, filtrated and the residue concentrated to a volume of 24 mL. 1b was purified using flash chromatography.

[0371] Yield: 5.31 g (148%, 6.66 mmol)

[0372] MS: m/z 796.38=[M+H]+, (calculated=795.37).

[0373] To a solution of 1b (5.31 g, max. 4.51 mmol ref. to N-Fmoc-N-Me-Asp(OBn)-OH) in THF (60 mL) DBU (1.8 mL, 3% v/v) was added. The solution was stirred for 12 min at RT, diluted with CH.sub.2Cl.sub.2 (400 ml) and washed 3× with 0.1 M H.sub.2SO.sub.4 (150 ml) and 3× with brine (150 ml). The aqueous phases were re-extracted with CH.sub.2Cl.sub.2 (100 ml). The combined organic phases were dried over Na.sub.2SO.sub.4 and filtrated. 1c was isolated upon evaporation of the solvent and used in the next reaction without further purification.

[0374] MS: m/z 574.31=[M+H].sup.+, (calculated=573.30).

[0375] 1c (5.31 g, 4.51 mmol, crude) was dissolved in acetonitrile (26 mL) and COMU (3.87 g, 9.04 mmol), 6-tritylmercaptohexanoic acid (2.12 g, 5.42 mmol) and collidine (2.35 mL, 18.08 mmol) were added. The reaction mixture was stirred for 4 h at RT, diluted with CH.sub.2Cl.sub.2 (400 mL) and washed 3× with 0.1 M H.sub.2SO.sub.4 (100 mL) and 3× with brine (100 mL). The aqueous phases were re-extracted with CH.sub.2Cl.sub.2 (100 ml). The combined organic phases were dried over Na.sub.2SO.sub.4, filtrated and 1d was isolated upon evaporation of the solvent. Product 1d was purified using flash chromatography.

[0376] Yield: 2.63 g (62%, 94% purity)

[0377] MS: m/z 856.41=[M+H].sup.+, (calculated=855.41).

[0378] To a solution of 1d (2.63 g, 2.78 mmol) in i-PrOH (33 mL) and H.sub.2O (11 mL) was added LiOH (267 mg, 11.12 mmol) and the reaction mixture was stirred for 70 min at RT. The mixture was diluted with CH.sub.2Cl.sub.2 (200 ml) and washed 3× with 0.1 M H.sub.2SO.sub.4 (50 ml) and 3× with brine (50 ml). The aqueous phases were re-extracted with CH.sub.2Cl.sub.2 (100 mL). The combined organic phases were dried over Na.sub.2SO.sub.4, filtrated and 1e was isolated upon evaporation of the solvent. 1e was purified using flash chromatography.

[0379] Yield: 2.1 g (88%)

[0380] MS: m/z 878.4=[M+Na].sup.+, (calculated=878.40).

[0381] Indazole (50 mg, 0.42 mmol) and PyBOP (264 mg, 0.51 mmol) were dissolved in DMF (1.5 mL). To the solution 1e (435 mg, 0.51 mmol) and DIPEA (222 μL, 1.27 mmol) were added with stirring. After 18 h the reaction solution was transferred into a separating funnel, diluted with 10 mL ethyl acetate and the organic phase was washed 1× with 10 mL 0.1 N HCl, 1×10 mL water and 1×10 mL brine. The organic phase was dried over Na.sub.2SO.sub.4, filtered and all volatiles were evaporated. 1f was purified by flash chromatography.

[0382] Yield: 173 mg (43%)

[0383] MS: m/z 956.72=[M+H].sup.+, (calculated=956.47).

[0384] 1f (80 mg, 84 μmol) was dissolved in HFIP/TES/H.sub.2O 39/1/1 (v/v/v) (1 mL). To the solution TFA (200 μL, 2.6 mmol) was added. All volatiles were removed in a stream of argon. Crude 1g was purified by RP-HPLC.

[0385] Yield: 9.6 mg (21%) TFA salt

[0386] MS: m/z 434.51=[M+H].sup.+, (calculated=434.22).

[0387] A mixture of 450 μL formic acid and 50 μL hydrogen peroxide was incubated at RT for 1 h and precooled in the fridge. 100 μL of this solution was added to 1g (2.50 mg; 4.6 μmol). After 10 min 100 μL water were added and the product 1h isolated by repetitive lyophilization.

[0388] Yield: 2 mg (86%) formic acid salt

[0389] MS: m/z 482.46=[M+H].sup.+, (calculated=482.21).

Example 2: Synthesis of 1-((4-nitrophenoxy)carbonyl)-1H-indazole-3-carboxylic acid 2

[0390] 1H-indazole-3-carboxylic acid (249 mg, 1.54 mmol) was suspended in DCM (5 mL) and a solution of 4-nitrophenyl chloroformate (343 mg; 1.70 mmol) in DCM (5 mL) was added with stirring. A suspension was obtained. TEA (645 μL, 4.63 mmol) was added with stirring. The reaction solution was diluted after 2 h with 150 ml ethyl acetate and the organic phase was washed 3× with 50 mL 0.1 M HCl. The aqueous phase was re-extracted 2× with 50 mL of ethyl acetate. The combined organic phase was dried over Na.sub.2SO.sub.4, filtered and the solvent was evaporated. The product 1-((4-nitrophenoxy)carbonyl)-1H-indazole-3-carboxylic acid 2 was used without further purification.

[0391] Yield: 486 mg (97%)

[0392] MS: m/z 327.99=[M+H].sup.+, (calculated=328.06).

Example 3: Synthesis of Compound 3

[0393] ##STR00054##

[0394] 4-nitrophenyl chloroformate (188 mg, 0.93 mmol) was dissolved in THF (8 mL). This solution was added to axitinib (100 mg, 0.26 mmol) and the reaction heated at 80° C. for 7 h with stirring (yellow suspension). The reaction suspension was left standing at RT overnight. The suspension was centrifuged, the supernatant removed, and the precipitate washed with ethyl acetate (2 times 6 ml). The precipitate was dried in high vacuum.

[0395] Yield: 139 mg (92%, HCl salt)

[0396] MS: m/z 552.11=[M+H].sup.+, (calculated=552.14).

Example 4: Synthesis of Compound 4a

[0397] ##STR00055##

[0398] N-benzyloxycarbonyl sarcosine (100 mg, 0.45 mmol) and HOBt (59 mg, 0.44 mmol) were suspended in DCM (1 mL). 1-propylamine (44 μL, 0.54 mmol) was added and a solution was obtained. EDC HCl (91 mg, 0.48 mmol) was added and the reaction stirred. After 4.5 h the reaction was concentrated in vacuo and the crude purified by RP-HPLC. The product was dissolved in THF (1.95 mL) by ultrasonication. To the solution 10% Palladium on activated charcoal (4.2 mg, 0.04 mmol) was added and the reaction was stirred in an atmosphere of hydrogen. After 3 h the reaction was filtered and the filtrate concentrated in vacuo.

[0399] Yield: 50 mg (86%)

[0400] MS: m/z 130.93=[M+H].sup.+, (calculated=131.12).

Example 5: Synthesis of Compound 4b

[0401] ##STR00056##

[0402] N-benzyloxycarbonyl sarcosine (103 mg, 0.46 mmol) was dissolved in DMF (1 mL) and 2-butylamine (54 μL, 0.53 mmol) and PyBOP (257 mg, 0.49 mmol) were added with stirring. A solution was obtained. DIPEA (156 μL, 0.90 mmol) was added. After 5 h the reaction was quenched with TFA (50 μl) and the product purified by RP-HPLC. The product step was dissolved in THF (2 mL). To the solution 10% Palladium on activated charcoal (4.5 mg, 0.04 mmol) was added and the reaction was stirred in an atmosphere of hydrogen. After 3 h the reaction was filtered, and the filtrate concentrated in vacuo.

[0403] Yield: 67 mg (quant)

[0404] MS: m/z 144.97=[M+H].sup.+, (calculated=145.14).

Example 6: Synthesis of Compound 4c

[0405] ##STR00057##

[0406] Boc-Sar-OH (99 mg, 0.52 mmol) was dissolved in DCM (1 mL). L-Valine tert-butyl ester hydrochloride (111 mg, 0.53 mmol), EDC HCl (109 mg, 0.57 mmol) and DIPEA (276 μL, 1.59 mmol) were added with stirring. After 3 h the reaction was diluted with 30 mL of DCM and was washed 3 times with 30 mL of 0.1 N HCl, 2 times with sat. NaHCO3 and once with brine. The organic phase was dried over Na.sub.2SO.sub.4, filtered and evaporated. The product was purified by RP-HPLC. The product was dissolved in 0.5 ml of DCM. 0.5 ml of TFA were added with stirring in an open flask. After 5 h the reaction was concentrated in a stream of nitrogen and the product co-evaporated 3 times with DCM.

[0407] Yield: 44 mg (28%, TFA salt)

[0408] MS: m/z 188.88=[M+H].sup.+, (calculated=189.13).

Example 7: Synthesis of Compound 4d

[0409] ##STR00058##

[0410] 3-[(tert-butoxycarbonyl)(methyl)amino]propanoic acid (102 mg, 0.50 mmol) was dissolved in DMF (0.5 mL). 1-propylamine (49 μL, 0.59 mmol), PyBOP (286 mg, 0.55 mmol) and DIPEA (171 μL, 0.98 mmol). After 3 h the reaction was quenched with TFA (50 μl) and the product purified by RP-HPLC. The product was dissolved in 0.5 ml of DCM. 0.5 mL of TFA were added with stirring in an open flask. After 1 h the reaction was concentrated in a stream of nitrogen and the product co-evaporated 2 times with DCM. The residue was dissolved in water (2 mL) and lyophilized.

[0411] Yield: 128 mg (99%, TFA salt)

[0412] MS: m/z 144.92=[M+H].sup.+, (calculated=145.14).

Example 8: Synthesis of Compound 4e

[0413] ##STR00059##

[0414] Methyl 6-oxo-heptanoate (2 g, 12.64 mmol) was dissolved in methanol (13 mL) and ammonium acetate (9.75 g, 126.43 mmol), and sodium cyanoborohydride (1.19 g, 18.96 mmol) was added with stirring. The resulting suspension turned into a solution and stirring was continued overnight. The mixture was diluted with water (70 mL) and ethyl acetate was added (80 mL). The pH of the water phase was adjusted to ca pH 11 with 25 mL 4 M NaOH. The water phase was extracted 3 more times with 70 mL ethyl acetate. The combined organic phases were dried (MgSO.sub.4), filtered and concentrated in vacuo. The crude from the first step was dissolved in DMF (20 mL) and N-Boc-N-ethylglycine (2.55 g, 12.56 mmol), PyBOP (7.19 g, 13.82 mmol) and DIPEA (6.56 mL, 37.68 mmol) were added with stirring. After 1 h the reaction was diluted with 60 mL ethyl acetate and washed with 0.1 M HCl (3 times 80 mL), 0.5 M NaOH (3 times 50 mL) and brine (50 mL). The organic phase was dried (MgSO.sub.4), filtered and concentrated in vacuo. The residue was purified using flash chromatography (heptane/ethyl acetate). The product was dissolved in THF (10 mL), and LiOH (0.46 g, 19.21 mmol) was dissolved in water (4 mL). The solutions were combined and stirred vigorously. After 3 h the reaction was diluted with 80 mL ethyl acetate and 60 mL 1 M HCl was added. The pH of the aqueous phase was below 2. The organic phase was collected and the aqueous phase extracted with ethyl acetate (2 times 50 mL). The combined organic solution was dried (MgSO.sub.4), filtered and concentrated in vacuo. The residue was dissolved in DCM (10 mL) and TFA (5 mL) was added with vigorous stirring in an open flask. After 30 min the reaction was concentrated in vacuo and co-evaporated once with 5 mL DCM. The crude was dissolved in water (40 mL) and lyophilized.

[0415] Yield: 2.54 g (59%, TFA salt)

[0416] MS: m/z 230.94=[M+H].sup.+, (calculated=231.17).

Example 9: Synthesis of Compound 4f

[0417] ##STR00060##

[0418] Compound 4f was synthesized using solid phase synthesis following the general protocol using Fmoc-Ahx-OH and Boc-N-ethyl glycine as building blocks. Upon cleavage from the resin the BOC protecting group was removed concurrently using the TFA cleavage cocktail. The cleavage solution was concentrated in vacuo, and the residue was dissolved in acetonitrile/water and lyophilized.

[0419] Yield: 1.01 g (quant., TFA salt)

[0420] MS: m/z 216.92=[M+H].sup.+, (calculated=217.16).

Example 10: Synthesis of Compound 4g

[0421] ##STR00061##

[0422] N-Boc-N-ethylglycine (100 mg, 0.49 mmol) and HOBt (66 mg, 0.49 mmol) were suspended in DCM (1 mL). H-beta-Ala-OtBu hydrochloride (107 mg, 0.59 mmol) was added and a solution was obtained. EDC HCl (99 mg, 0.52 mmol) was added and the reaction was stirred for 1.5 h. The volatiles were removed in vacuo and the product purified by RP-HPLC. The product was dissolved in 0.5 mL of DCM. 0.5 mL of TFA were added with stirring in an open flask. After 30 min the reaction was concentrated in vacuo and the product co-evaporated 2 times with DCM. The residue was dissolved in acetonitrile/water 1:1 (2 mL) and lyophilized.

[0423] Yield: 125 mg (88%, TFA salt)

[0424] MS: m/z 174.98=[M+H].sup.+, (calculated=175.11).

Example 11: Synthesis of Compound 4h

[0425] ##STR00062##

[0426] N-Boc-N-ethylglycine (102 mg, 0.50 mmol) was dissolved in DMF (0.5 mL). 1-propylamine, (49 μL, 0.59 mmol), PyBOP (281 mg, 0.54 mmol) and DIPEA (171 μL, 0.98 mmol) were added. After 3.5 h TFA (40 μL) was added and the product purified by RP-HPLC. The product was dissolved in 0.5 ml of DCM. 0.5 ml of TFA were added with stirring in an open flask. After 1 h the reaction was concentrated in vacuo and the product co-evaporated 2 times with DCM (2 mL).

[0427] Yield: 122 mg (94%, TFA salt)

[0428] MS: m/z 144.89=[M+H].sup.+, (calculated=145.14).

Example 12: Synthesis of Compound 4i

[0429] ##STR00063##

[0430] To a suspension of trans-4-hydroxycyclohexanoic acid (61 mg, 0.43 mmol) in DCM (0.8 mL) was added HOBt (63 mg, 0.47 mmol) then DIC (73 μL, 0.47 mmol). To the suspension was added DMF (0.2 mL). H-beta-Ala-OtBu hydrochloride (86 mg, 0.47 mmol) in DCM (0.2 mL). After 4.5 h DIPEA (60 μL) was added. After 5 h the reaction was diluted with DCM (ca. 10 mL) and filtered. The filtrate was washed with aq. 0.1 M HCl, then with brine. The organic phase was dried over MgSO.sub.4, filtered and concentrated in vacuo. The product was purified by RP-HPLC. The product (57.00 mg, 0.21 mmol) was dissolved in DCM (2.5 mL) and DMAP (26 mg, 0.21 mmol) was added. 4-nitrophenyl chloroformate (85 mg, 0.42 mmol) in DCM (0.5 mL) and DIPEA (110 μL, 0.63 mmol) were added. After 1 h 0.1 M aq. HCl (15 mL) was added and the mixture diluted with ethyl acetate (30 mL). The organic phase was washed with 0.1 M aq. HCl (2 times 10 mL). The aq phase was re-extracted with ethyl acetate (3 times 10 mL). The organic phases were combined, dried over MgSO.sub.4, filtered, and concentrated in vacuo.

[0431] Yield: 119 mg (65%)

[0432] MS: m/z 437.21=[M+H].sup.+, (calculated=437.19).

Example 13: Synthesis of Compound 4j

[0433] ##STR00064##

[0434] Boc-Sar-OH (103 mg, 0.54 mmol) was dissolved in DCM (1 mL). tert-Butyl-(3S)-3-aminobutanoate (84 mg, 0.53 mmol), EDC HCl (113 mg, 0.59 mmol) and DIPEA (0.28 mL, 1.58 mmol) were added. After 3 h the reaction mixture was diluted with 30 mL of DCM and was washed 3 times with 30 mL of 0.1 N HCl, 2 times with sat. NaHCO.sub.3 and once with brine. The organic phase was dried over Na.sub.2SO.sub.4, filtered and evaporated. The product was purified by RP-HPLC. The product was dissolved in 0.5 mL of DCM. 0.5 ml of TFA were added with stirring in an open flask. After 3 h the reaction was concentrated in vacuo and the product co-evaporated 3 times with DCM (5 mL).

[0435] Yield: 73 mg (47%)

[0436] MS: m/z 437.21=[M+H].sup.+, (calculated=437.19).

Example 14: Synthesis of Compound 5a

[0437] ##STR00065##

[0438] 5a was synthesized using solid phase synthesis following the general protocol using Fmoc-Ahx-OH, Fmoc-beta homoalanine-OH and Fmoc-Sar-OH as building blocks.

Example 15: Synthesis of Compound 5b

[0439] ##STR00066##

[0440] 5b was synthesized using solid phase synthesis following the general protocol using Fmoc-Ahx-OH, Fmoc-Ala-OH and Fmoc-Sar-OH as building blocks.

Example 16: Synthesis of Compound 5c

[0441] ##STR00067##

[0442] 5c was synthesized using solid phase synthesis following the general protocol using Fmoc-Ahx-OH, and Fmoc-N-Methyl-Ala-OH as building blocks.

Example 17: Synthesis of Compound 5d

[0443] ##STR00068##

[0444] 5c was synthesized using solid phase synthesis following the general protocol using Fmoc-Ahx-OH, and Fmoc-Pro-OH as building blocks.

Example 18: Synthesis of Compound 6a

[0445] ##STR00069##

[0446] 1H-indazole-3-carboxylic acid (40 mg, 0.25 mmol) was dissolved in DMF (0.5 mL). DIPEA (172 μL, 0.99 mmol) and n-butyl chloroformate (63 μL, 0.49 mmol) were added. The mixture was stirred for 2.5 h. TFA (95 μL) was added and the product was purified by RP-HPLC.

[0447] Yield: 0.8 mg (1%)

[0448] MS: m/z 262.91=[M+H].sup.+, (calculated=263.11).

Example 19: Synthesis of Compound 6b

[0449] ##STR00070##

[0450] 4-nitrophenyl chloroformate (50 mg, 0.25 mmol) was dissolved in DCM (0.50 mL). To the stirred reaction 2-pentanol (25 μL, 0.23 mmol) and TEA (79 μL, 0.57 mmol) were added. After 4 h volatiles were removed in a stream of nitrogen and the product purified by RP-HPLC. The product (17 mg, 0.07 mmol) was dissolved in 0.5 mL acetonitrile and 1H-indazole-3-carboxylic acid (10 mg, 0.06 mmol) was added. DIPEA (27 μL, 0.15 mmol) was added. After 2 h again DIPEA (27 μL, 0.15 mmol) was added. After 4 h acetic acid (100 μL) was added and the product purified by RP-HPLC.

[0451] Yield: 15 mg (53%)

[0452] MS: m/z 277.12=[M+H].sup.+, (calculated=277.12).

Example 20: Synthesis of Compound 6c

[0453] ##STR00071##

[0454] 1H-indazole-3-carboxylic acid (20 mg, 0.12 mmol) and di-tert-butyl dicarbonate (30 mg, 0.14 mmol) were suspended in acetonitrile (0.50 mL). DMAP (1.5 mg, 0.01 mmol) and DIPEA (32 μL, 0.19 mmol) were added and the reaction stirred for 2.25 h. The product was purified by RP-HPLC.

[0455] Yield: 18 mg (56%)

[0456] MS: m/z 547.18=[2M+Na].sup.+, (calculated=547.18).

Example 21: Synthesis of Compound 6d

[0457] ##STR00072##

[0458] H-beta-Ala-OtBu hydrochloride (245 mg, 1.35 mmol) was dissolved in DMF (3 mL) and cooled under stirring in an ice-bath for 10 min before sequential addition of DIPEA (250 μL, 1.44 mmol), gamma-valerolactone (86 μL, 0.90 mmol) and tin(II)acetate (46 mg, 0.20 mmol). After 5 more minutes of cooling, the solution was heated to 80° C. with stirring for 6.75 h. The reaction was diluted with ethyl acetate (25 mL), washed with 0.1 M aq. HCl (30 mL) and brine (2 times 25 mL). The combined organic phases were dried (MgSO.sub.4), filtered and concentrated in vacuo. The product was purified by RP-HPLC.

[0459] The aforementioned product (4 mg, 16 μmol) was dissolved in DCM (0.2 mL) and 4-nitrophenyl chloroformate (6.5 mg, 32 μmol) in DCM (50 μL) was added. DIPEA (8 μL, 46 μmol) and DMAP (1.9 mg, 16 μmol) were added. After 2 h the reaction was quenched by addition of 0.1 M aq. HCl (2 mL) and diluted with ethyl acetate (ca. 2 mL). The organic phase was extracted, and then the aq. phase re-extracted with ethyl acetate (4 times ca. 2 mL). The organics were combined and dried over MgSO.sub.4, filtered, and the volatiles removed in vacuo. The activated PNP carbonate from the previous step was used without further purification. 1H-indazole-3-carboxylic acid (3.2 mg, 20 μmol) in DCM (0.4 ml) was added. DIPEA (9 μL, 52 μmol) was added and the reaction stirred overnight. The product was purified by RP-HPLC. The product from the former step was dissolved in DCM (0.4 mL) and TFA (0.2 mL) was added. After 1 h volatiles were removed in vacuo and the residue dissolved in water and lyophilized.

[0460] Yield: 1.7 mg (0.6%)

[0461] MS: m/z 378.06=[M+H].sup.+, (calculated=378.13).

Example 22: Synthesis of Compound 6e

[0462] ##STR00073##

[0463] H-Thr-OtBu (59 mg, 0.28 mmol) was dissolved in DMF (0.5 mL), and DIPEA (145 μL, 0.84 mmol) was added. After 5 min, N-acetoxysuccinimide (54 mg, 0.34 mmol) in DMF (0.2 mL) was added drop-wise. After 40 min the reaction was diluted with ethyl acetate (15 mL) then washed sequentially with 0.1 M aq. HCl (3 times 10 mL), sat. NaHCO.sub.3 (2 times 10 mL) and brine (2 times 10 mL). The organic phase was dried over MgSO.sub.4, filtered, and concentrated in vacuo. The product was purified by RP-HPLC.

[0464] To a stirred solution of the product from the former step (4.6 mg, 21 μmol) in DCM (0.2 mL) was added 4-nitrophenyl chloroformate (8.7 mg, 43 μmol) in DCM (0.1 ml). Under stirring DIPEA (11 IL, 63 μmol) and DMAP (2.7 mg, 22 μmol) were added. After 2.25 h the reaction was diluted with ethyl acetate (ca. 2 mL) then washed with 0.1 M aq. HCl (2 mL). Re-extracted from the aq. phase with ethyl acetate (3 times ca. 3 mL). The organics were combined, dried over MgSO.sub.4, filtered and concentrated in vacuo.

[0465] The activated PNP carbonate from the previous step was used without further purification. 1H-indazole-3-carboxylic acid (4.7 mg, 29 μmol) in DCM (0.4 mL) was added. DIPEA (11 IL, 63 μmol) was added. After stirring overnight, the volatiles were removed in vacuo and the product was purified by RP-HPLC. The product from the former step was dissolved in DCM (0.4 mL) and TFA (0.2 mL) was added. After 4 h volatiles were removed in vacuo and the residue dissolved in water and lyophilized.

[0466] Yield: 1.1 mg (11.2%, TFA salt)

[0467] MS: m/z 350.06=[M+H].sup.+, (calculated=350.10).

Example 23: Synthesis of Compound 6f

[0468] ##STR00074##

[0469] 4i (22.9 mg, 52 μmol) and 1H-indazole-3-carboxylic acid (7.5 mg, 46 μmol) were suspended in DCM (0.55 mL). DIPEA (25 μL, 144 μmol) was added and the reaction stirred overnight. More DIPEA (3 times 8.5 μl) was added after 1 h, 1.5 h, 3.5 h. Next day the reaction was diluted with ethyl acetate (25 mL) and washed with 0.1 M aq. HCl (2 times 10 mL) and brine (10 mL). The organic phase was dried over Na.sub.2SO.sub.4, filtered and concentrated in vacuo. The product was purified by RP-HPLC. The product from the former step (2.3 mg) was dissolved in DCM (0.1 mL) and TFA (0.1 mL) was added. After 2.25 h volatiles were removed in vacuo and the residue dissolved in water and lyophilized.

[0470] Yield: 1.6 mg (38%)

[0471] MS: m/z 460.15=[M+H].sup.+, (calculated=460.21).

Example 24

[0472] ##STR00075## ##STR00076##

[0473] Conjugates 7a-k were synthesized by reacting 1 eq. of 2 with 1.0-1.2 eq. of the respective amine 4a-h or for 7i: 1-propylamine, 7j: N,N,N′-trimethylethylene, 7k: N,N,N′-trimethyl-1,3-propane diamine using excess DIPEA in DMF. Reactions were quenched using excess TFA and purified by RP-HPLC.

[0474] 7a: 2: 19 mg, 59 μmol, 4a: 9 mg, 69 μmol, DIPEA: 21 μL, 0.12 mmol:

[0475] Yield: 2.1 mg (11%), MS: m/z 319.09=[M+H].sup.+, (calculated=319.14).

[0476] 7b: 2: 20 mg, 60 μmol, 4b: 12 mg, 69 μmol, DIPEA: 21 μL, 0.12 mmol:

[0477] Yield: 5.5 mg (27%), MS: m/z 333.11=[M+H].sup.+, (calculated=333.16).

[0478] 7c: 2: 10 mg, 31 μmol, 4c: 11 mg, 35 μmol, DIPEA: 21 μL, 0.12 mmol:

[0479] Yield: 2.3 mg (19%), MS: m/z 377.06=[M+H].sup.+, (calculated=377.15).

[0480] 7d: 2: 21 mg, 65 μmol, 4d: 18 mg, 66 μmol, DIPEA: 43 μL, 0.25 mmol:

[0481] Yield: 6.5 mg (30%), MS: m/z 333.11=[M+H].sup.+, (calculated=333.16).

[0482] 7e: 2: 17 mg, 51 μmol, 4e: 17 mg, 49 μmol, DIPEA: 21 μL, 0.12 mmol:

[0483] Yield: 3.9 mg (18%), MS: m/z 419.17=[M+H].sup.+, (calculated=419.20).

[0484] 7f: 2: 10 mg, 31 μmol, 4f: 11 mg, 34 μmol, DIPEA: 21 μL, 0.12 mmol:

[0485] Yield: 1.7 mg (14%), MS: m/z 405.03=[M+H].sup.+, (calculated=405.18).

[0486] 7g: 2: 20 mg, 60 μmol, 4g: 24 mg, 69 μmol, DIPEA: 21 μL, 0.12 mmol:

[0487] Yield: 1.9 mg (9%), MS: m/z 363.03=[M+H].sup.+, (calculated=363.13).

[0488] 7h: 2: 20 mg, 60 μmol, 4h: 24 mg, 68 μmol, DIPEA: 43 μL, 0.25 mmol:

[0489] Yield: 4 mg (20%), MS: m/z 333.18=[M+H].sup.+, (calculated=333.16).

[0490] 7i: 2: 22 mg, 66 μmol, 4i: 5 μl, 61 μmol, DIPEA: 21 μL, 0.12 mmol:

[0491] Yield: 4.7 mg (29%), MS: m/z 247.96=[M+H].sup.+, (calculated=248.11).

[0492] 7j: 2: 16 mg, 50 μmol, 4j: 8 μl, 62 μmol, DIPEA: 21 μL, 0.12 mmol:

[0493] Yield: 8 mg (52%), MS: m/z 291.03=[M+H].sup.+, (calculated=291.15).

[0494] 7k: 2: 21 mg, 65 μmol, 4k: 9.4 μl, 64 μmol, DIPEA: 21 μL, 0.12 mmol:

[0495] Yield: 0.4 mg (1%), MS: m/z 305.06=[M+H].sup.+, (calculated=305.16).

Example 25

[0496] ##STR00077##

[0497] Conjugates 8a-e were synthesized by Fmoc deprotection of 5a-d using 2:2:96 piperidine/DBU/DMF, following reacting an excess of 2 with the respective amine on resin using excess DIPEA in DMF. The product was cleaved from the resin using HFIP and purified by RP-HPLC.

[0498] 8a: 5a: 7 mg, 5 μmol, 2: 5 mg, 16 μmol, DIPEA: 5 μL, 31 μmol

[0499] Yield: 1.1 mg (45%), MS: m/z 476.02=[M+H].sup.+, (calculated=476.22).

[0500] 8b: 5b: 7 mg, 5 μmol, 2: 5 mg, 15 μmol, DIPEA: 5 μl, 31 μmol

[0501] Yield: 1.3 mg (55%), MS: m/z 462.12=[M+H].sup.+, (calculated=462.20).

[0502] 8c: 5c: 50 μmol, 2: 44 mg, 0.13 mmol, DIPEA: 50 μl, 0.29 mmol

[0503] Yield: 6.5 mg (32%), MS: m/z 405.16=[M+H].sup.+, (calculated=405.18).

[0504] 8d: 5d: 55 μmol, 2: 52 mg, 0.16 mmol, DIPEA: 55 μl, 0.32 mmol

[0505] Yield: 11 mg (48%), MS: m/z 417.16=[M+H].sup.+, (calculated=417.18).

Example 26: Synthesis of Compound 9a

[0506] ##STR00078##

[0507] 4g (29 mg, 82 μmol) was dissolved in 100 μL of DMF and DIPEA (48 μL, 0.27 mmol) was added. A suspension of 3 (40 mg, 68 μmol) (0.79 mL in DMF) was added. After 3.5 h 4g (14 mg, 41 μmol) in 50 μL of DMF was added. After 4.75 h TFA (21 μL) were added and the reaction purified by RP-HPLC.

[0508] Yield: 22 mg (45%, TFA salt)

[0509] MS: m/z 350.06=[M+H].sup.+, (calculated=350.10).

Example 27: Synthesis of Compound 9b

[0510] ##STR00079##

[0511] 4j (28 mg, 88 μmol) was dissolved in 100 μL of DMF and DIPEA (38 μL, 0.22 mmol) was added. A suspension of 3 (26 mg, 44 μmol) (508 μL in DMF) was added. After 30 min TFA (6.7 μL) was added and the product purified by RP-HPLC.

[0512] Yield: 31 mg (quant, TFA salt)

[0513] MS: m/z 587.16=[M+H].sup.+, (calculated=587.21).

Example 28: Synthesis of Compound 9c

[0514] ##STR00080##

[0515] 4c (22 mg, 68 μmol) was dissolved in 100 μL of DMF and DIPEA (30 μL, 0.17 mmol) was added. A suspension of 3 (20 mg, 34 μmol) (393 μL in DMF) was added. After 1 h TFA (5.2 μl) was added and the product purified by RP-HPLC.

[0516] Yield: 26 mg (quant, TFA salt)

[0517] MS: m/z 601.10=[M+H].sup.+, (calculated=601.23).

Example 29: Synthesis of Compounds 9d and 9e

[0518] ##STR00081##

[0519] 4f (689 mg, 2.09 mmol) was dissolved in 4 mL of DMF and DIPEA (0.9 mL, 5.2 mmol) was added. A suspension of 3 (0.61 g, 0.98 mmol) (8.2 mL in DMF) was added. After 30 min the reaction was added to a solution of 2.6 mL 4 N HCl in dioxane and 237 mL of ethyl acetate. The precipitate was centrifuged, the supernatant decanted and the residue washed once with 180 mL ethyl acetate. The residue was purified by RP-LPLC to obtain compound 9d.

[0520] Yield: 0.34 g (46%, TFA salt)

[0521] MS: m/z 629.34=[M+H].sup.+, (calculated=629.26).

[0522] 9d (0.34 g; 0.45 mmol) was dissolved in DMF (6.76 mL) and bis(pentafluorophenyl) carbonate (0.21 g, 0.54 mmol) was added. DIPEA (0.48 mL, 2.73 mmol) was added. After 45 min acetic acid (0.48 mL) was added and the product purified by RP-LPLC to obtain compound 9e.

[0523] Yield: 0.40 g (98%, TFA salt)

[0524] MS: m/z 795.39=[M+H].sup.+, (calculated=795.24).

Example 30: Synthesis of Compound 9f

[0525] ##STR00082##

[0526] A suspension of 3 (8.50 mL, 0.13 mol/L; 1.04 mmol) in DMF was added to 4e (0.72 g, 2.08 mmol) and DIPEA (0.91 mL, 5.21 mmol) was added. After 45 min the reaction was added to a solution of 2.6 mL 4 N HCl in dioxane and 160 mL of ethyl acetate. The precipitate was centrifuged, the supernatant decanted and the residue purified by RP-LPLC.

[0527] The product from the former step (0.42 g, 0.55 mmol) was dissolved in DMF (8.40 mL) and bis(pentafluorophenyl) carbonate (0.27 g, 0.67 mmol) was added. DIPEA (0.58 mL, 3.33 mmol) was added. After 1 h acetic acid (0.48 mL) was added and the product purified by RP-LPLC.

[0528] Yield: 0.27 g (28%, TFA salt)

[0529] MS: m/z 809.36=[M+H].sup.+, (calculated=809.26).

Example 31: Synthesis of Compound 9g

[0530] ##STR00083##

[0531] A solution of 4i (49 mg, 0.11 mmol) in THF (1.60 mL) was added to axitinib (22 mg, 56 μmol). DIPEA (49 μL, 0.28 mmol) was added. The reaction was heated to 60° C. for 6 h and stirred overnight at RT. DMF (0.5 ml) was added. The reaction was heated to 60° C. for 6.5 h and stirred for 3 days at RT. DMAP (>1 eq.) was added and the reaction stirred at RT for 1 day. TFA (25 μL) was added and the product purified by RP-HPLC.

[0532] The product from the former step (16 mg, 20 μmol) was dissolved in a mixture of DCM (1 mL) and TFA (1 mL). After 2 h the volatiles were removed in vacuo and the residue dissolved in 3 mL acetonitrile/water/TFA 1:1:0.002 and lyophilized.

[0533] The product from the former step (15 mg, 20 μmol) was dissolved in DMF (0.29 mL) and bis(pentafluorophenyl) carbonate (9.4 mg 24 μmol) was added. DIPEA (21 μL; 0.12 mmol) was added. After 1.5 h TFA (10 μL) was added and the reaction purified by RP-HPLC.

[0534] Yield: 13 mg (25%, TFA salt)

[0535] MS: m/z 794.25=[M+H].sup.+, (calculated=794.21).

Example 32: Synthesis of Compounds 10a-d

[0536] ##STR00084## ##STR00085##

[0537] Methoxy polyethylene glycol amine-5 kDa PEG, PyBOP, DIPEA and 9 were stirred at RT. After the reaction was finished, acetic acid was added, and the product purified by RP-HPLC.

[0538] 10a: PEG: 33 mg, 6.0 μmol, PyBOP: 3.6 mg, 6.9 μmol, DIPEA: 3.1 μl, 18 μmol, 9a: 4.2 mg, 6 μmol, yield: 21 mg (58%, TFA salt).

[0539] 10b: PEG: 21 mg, 3.8 μmol, PyBOP: 3.5 mg, 6.7 μmol, DIPEA: 1.9 μl, 11 μmol, 9b: 2.6 mg, 3.7 μmol, yield: 18 mg (77%, TFA salt).

[0540] 10c: PEG: 47 mg, 8.5 μmol, PyBOP: 4.9 mg, 9.4 μmol, DIPEA: 4.4 μl, 25 μmol, 9c: 6 mg, 8.4 μmol, yield: 31 mg (60%, TFA salt).

[0541] 10d: PEG: 31 mg, 5.6 μmol, PyBOP: 3.5 mg, 6.8 μmol, DIPEA: 2.8 μL, 16 μmol, 9d: 4 mg, 5.4 μmol, yield: 34 mg (quant, TFA salt).

Example 33: Synthesis of Compounds 11a-d

[0542] ##STR00086##

[0543] The hydrogel was swollen in 1% DIPEA in DMF in a syringe reactor containing a PE frit. The syringe reactor was 3 times filled, shaken for 1 min and drained. 9 was dissolved in DMF and DIPEA was added. The solution was drawn into the syringe containing the hydrogel. The syringe was shaken for longer than 16 h at RT. The syringe was drained, and the hydrogel was washed several times with DMF and ethanol and dried in vacuo or washed several times with DMF, water and pH 5.5 20 mM sodium succinate aqueous buffer and a hydrogel suspension in pH 5.5 aqueous buffer was obtained.

[0544] 11a: HG-1: 14 mg, DIPEA: 1.6 μL, 9e: 3 mg,

[0545] yield: 15 mg, dried 39 mg/g axitinib in dried hydrogel.

[0546] 11b: HG-2: 0.82 g, DIPEA: 0.21 mL, 9e: 0.40 g

[0547] yield: suspension, 7.55 mg/mL axitinib in hydrogel suspension.

[0548] 11c: HG-3: 30 mg, DIPEA: 3.5 μL, 9f: 6.7 mg,

[0549] yield: suspension, 2.93 mg/mL axitinib in hydrogel suspension.

[0550] 11d: HG-3: 30 mg, DIPEA: 3.5 μL, 9g: 13 mg

[0551] yield: suspension, 3.65 mg/mL axitinib in hydrogel suspension.

Example 34: In Vitro Release Kinetics

[0552] The cleavage rate of the reversible bond from conjugates 6a-f, 7a-k, 8a-d, 10a-d, 11a-d was monitored at pH 7.4 and 37° C. in aqueous buffer (pH 7.4 48 mM sodium phosphate, 20% acetonitrile or pH 7.4 60 mM sodium phosphate). For soluble examples disappearance of the conjugate was determined by LCMS (UV detection) and fitted with curve fitting software to obtain the preliminary half-life of the release. For insoluble examples (hydrogels) the increase in released heteroaromatic moiety containing molecule in the supernatant was determined by LCMS (UV detection) and used as input for the curve fitting software to obtain the preliminary half-life of the release.

TABLE-US-00001 Compound t.sub.1/2 (pH 7.4) Released product 1 h** <1 min indazole  6a*   21 d 1H-indazole-3-carboxylic acid  6b*   99 d 1H-indazole-3-carboxylic acid  6c*    2 h 1H-indazole-3-carboxylic acid  6d*   36 d 1H-indazole-3-carboxylic acid  6e*   1 d 1H-indazole-3-carboxylic acid  6f*   39 d 1H-indazole-3-carboxylic acid  7a*  3.5 d 1H-indazole-3-carboxylic acid  7b*   17 d 1H-indazole-3-carboxylic acid  7c* >180 d 1H-indazole-3-carboxylic acid  7d* >180 d 1H-indazole-3-carboxylic acid  7e*   52 d 1H-indazole-3-carboxylic acid  7f*  9.6 d 1H-indazole-3-carboxylic acid  7g*  7.7 d 1H-indazole-3-carboxylic acid  7h*  8.1 d 1H-indazole-3-carboxylic acid  7i* >180 d 1H-indazole-3-carboxylic acid  7j*  2.9 h 1H-indazole-3-carboxylic acid  7k*  164 d 1H-indazole-3-carboxylic acid  8a*  2.4 d 1H-indazole-3-carboxylic acid  8b*  8.2 h 1H-indazole-3-carboxylic acid  8c*   13 d 1H-indazole-3-carboxylic acid  8d*   12 d 1H-indazole-3-carboxylic acid 10a   14 h axitinib 10b   19 h axitinib 10c    8 h axitinib 10d  1.9 d axitinib 11a  3.7 d axitinib 11b  5.4 d axitinib 11c 17.4 d axitinib 11d   62 d axitinib

[0553] The compounds marked with “*” and “**” are not in accordance with the present invention as they were for efficiency reasons not linked to a moiety Z. Nevertheless, they show the release half-lives of such moieties -L.sup.1-. Compounds marked with “**” were synthesized for comparison.

Example 35: Synthesis of Compound 12a

[0554] ##STR00087##

[0555] 12a was synthesized using solid phase synthesis following the general protocol using Fmoc-N-methyl-beta-alanine, Fmoc-beta-homoalanine-OH and Fmoc-Sar-OH as building blocks.

Example 36: Synthesis of Compound 12b

[0556] ##STR00088##

[0557] 12b was synthesized using solid phase synthesis following the general protocol using Fmoc-beta-homoalanine-OH and Fmoc-Sar-OH as building blocks.

Example 37: Synthesis of Compound 12c

[0558] ##STR00089##

[0559] 12c was synthesized using solid phase synthesis following the general protocol using Fmoc-Ahx-OH, (S)-Fmoc-4-aminopentanoic acid, and Fmoc-Sar-OH as building blocks.

Example 38: Synthesis of Compound 12d

[0560] ##STR00090##

[0561] 12d was synthesized using solid phase synthesis following the general protocol using Fmoc-8-amino-3,6-dioxaoctanoic acid and Fmoc-N-Ethyl-Gly-OH as building blocks.

Example 39: Synthesis of Compound 12e

[0562] ##STR00091##

[0563] 12e was synthesized using solid phase synthesis following the general protocol using Fmoc-Ahx-OH, Fmoc-aminooxyacetic acid and Fmoc-Sar-OH as building blocks and using HFIP for cleavage from the resin. It was then purified by RP-HPLC.

[0564] Yield: 2.4 mg

[0565] MS: m/z 484.20=[M+H].sup.+, (calculated=484.20).

Example 40: Synthesis of Compounds 13a-d

[0566] ##STR00092##

[0567] Conjugates 13a-d were synthesized by Fmoc deprotection of 12a-d using 2:2:96 piperidine/DBU/DMF, following reacting an excess of 2 with the respective amine on resin using excess DIPEA in DMF. The product was cleaved from the resin using HFIP and purified by RP-HPLC.

[0568] 13a: 12a: 32 mg, 24 μmol, 2: 20 mg, 60 μmol, DIPEA: 17 μL, 96 μmol

[0569] Yield: 5.1 mg (48%), MS: m/z 448.15=[M+H].sup.+, (calculated=448.18).

[0570] 13b: 12b: 37 mg, 27 μmol, 2: 22 mg, 68 μmol, DIPEA: 19 μL, 109 μmol

[0571] Yield: 5.2 mg (43%), MS: m/z 448.15=[M+H].sup.+, (calculated=448.18).

[0572] 13c: 12c: 32 μmol, 2: 26 mg, 79 μmol, DIPEA: 22 μL, 127 μmol

[0573] Yield: 6.5 mg (42%), MS: m/z 490.20=[M+H].sup.+, (calculated=490.23).

[0574] 13d: 12d: 26 μmol, 2: 21 mg, 64 μmol, DIPEA: 18 μL, 102 μmol

[0575] Yield: 2.9 mg (26%), MS: m/z 437.14=[M+H].sup.+, (calculated=437.16).

Example 41: Synthesis of Compounds 13e

[0576] ##STR00093##

[0577] Compound 12e (2.4 mg, 0.005 mmol) in DMF (0.5 mL) was treated with piperidine (50 μL). After stirring at RT for 1 h, the mixture was diluted with DCM and the volatiles removed in vacuo. The residues were combined with 2 (2.4 mg; 0.007 mmol) in DMF (0.2 mL) and DIPEA (2.6 μL; 0.015 mmol; 3.0 eq.) was added. After stirring at RT for 65 min, TFA (1.1 μL) was added. The volatiles were removed in vacuo and the residues redissolved in 1:3 acetonitrile/H.sub.2O and freeze-dried. The residues were again combined with 2 (2.7 mg; 0.008 mmol) in DMF (0.2 mL) and DIPEA (5.0 μL; 0.029 mmol; 3.0 eq.) was added. After stirring at RT for 2.5 h, TFA (1.5 μL) was added. The volatiles were removed in vacuo and the residues redissolved in 1:3 acetonitrile/H.sub.2O and freeze-dried, and the crude purified by RP-HPLC

[0578] Yield: 0.1 mg (3%)

[0579] MS: m/z 450.10=[M+H].sup.+, (calculated=450.16)

Example 42: Synthesis of Compound 14a

[0580] ##STR00094##

[0581] Methyl 6-oxo-heptanoate (2 g, 12.6 mmol) was dissolved in methanol (13 mL) and ammonium acetate (9.75 g, 126 mmol), and sodium cyanoborohydride (1.19 g, 19.0 mmol) was added with stirring. The resulting suspension turned into a solution and stirring was continued overnight. The mixture was diluted with water (70 mL) and ethyl acetate was added (80 mL). The pH of the water phase was adjusted to circa pH 11 with 25 mL 4 M NaOH. The aqueous phase was extracted with ethyl acetate (three times 70 mL). The combined organic phases were dried (MgSO.sub.4), filtered and concentrated in vacuo to give a yellow oil (1.83 g). A portion of the crude oil (200 mg) from the first step was dissolved in DMF (2 mL) and N-Boc-Sar-OH (238 mg, 1.26 mmol), PyBOP (719 mg, 1.38 mmol) and DIPEA (656 μL, 3.77 mmol) were added with stirring. The reaction was stirred at RT for 2 h. The mixture was diluted with 25 mL ethyl acetate and washed with 0.1 N HCl (3 times 15 mL), 0.5 M NaOH (3 times 15 mL) and brine (15 mL). The organic phase was dried (MgSO.sub.4), filtered and concentrated in vacuo. The residue was purified using flash chromatography (heptane/ethyl acetate). The product (235 mg) was dissolved in THF (1 mL), and LiOH (51 mg, 2.13 mmol) was dissolved in water (0.4 mL). The solutions were combined and stirred vigorously at RT. After 5 h the mixture was diluted with 80 mL ethyl acetate, and 60 mL 1 N HCl was added. The pH of the aqueous phase was below 2. The organic phase was collected, and the aqueous phase extracted with ethyl acetate (three times 20 mL). The combined organics were dried (MgSO.sub.4), filtered, and concentrated in vacuo. The residue was dissolved in DCM (1.0 mL) and TFA (0.5 mL) was added with vigorous stirring in an open flask. After 75 min the reaction was concentrated in vacuo and co-evaporated once with 5 mL DCM. The crude was dissolved in 1:2 acetonitrile/H.sub.2O+0.1% TFA (20 mL) and lyophilized.

[0582] Yield: 213 mg (47%, TFA salt)

[0583] MS: m/z 217.05=[M+H].sup.+, (calculated=217.15).

Example 43: Synthesis of Compound 14b

[0584] ##STR00095##

[0585] Methyl 5-oxohexanoate (2.00 g, 13.9 mmol) was dissolved in THF (60 mL) and LiOH (1.00 g, 41.6 mmol) and water (20 mL) were added. The mixture was stirred at RT for 5 h before dilution with ethyl acetate (300 mL). 1 N aq.HCl (80 mL) was added, and the aqueous phase extracted with ethyl acetate (2 times 100 mL). The combined organics were dried (MgSO.sub.4) and concentrated in vacuo. The resulting colorless oil (1.6 g) was dissolved in DMF (32 mL), and PyBOP (7.68 g, 14.8 mmol) then DIPEA (10.7 mL, 61.5 mmol) were added to the mixture. After stirring for 5 min tert-butyl 3-aminopropanoate hydrochloride (2.69 g, 14.8 mmol) was added and the mixture stirred at RT for 105 min. The mixture was diluted with ethyl acetate (400 mL) and washed with 0.55 M aq. HCl (100 mL), 0.1 M aq. HCl (2 times 100 mL), sat. NaHCO.sub.3 (3 times 100 mL), and brine (100 mL). The organics were dried (MgSO.sub.4) and concentrated in vacuo before being purified by flash chromatography (ethyl acetate/heptane). The purified material was then dissolved in MeOH (14.2 mL) and ammonium acetate (6.60 g, 85.6 mmol) and sodium cyanoborohydride (801 mg; 12.8 mmol) were added. The mixture was stirred overnight at RT. The mixture was diluted with water (70 ml) and ethyl acetate (80 ml). Using 4 M NaOH (15 mL) the pH of the aq. phase was adjusted to ca. pH 2. The aq. phase was extracted with ethyl acetate (3 times 70 mL), the organics combined and TFA (648 μL) added. To the aq. phase was added further 4 M NaOH (5 mL) and again it was extracted with ethyl acetate (3 times 70 mL), these organics were combined and TFA (400 μL) added. The organics were dried (MgSO.sub.4), filtered, and the volatiles removed in vacuo.

[0586] Yield: 3.40 g (66%, TFA salt)

[0587] MS: m/z 259.12=[M+H].sup.+, (calculated=259.20).

Example 44: Synthesis of Compound 14c

[0588] ##STR00096##

[0589] Compound 14b (249 mg, 0.62 mmol) was dissolved in DMF (2.30 mL) and N-Boc-N-ethylglycine (132 mg, 0.65 mmol) and PyBOP (353 mg; 0.68 mmol) were added followed by DIPEA (326 μL, 1.87 mmol) to form a light yellow solution. After stirring at RT for 90 min, the mixture was diluted with ethyl acetate (50 mL) and washed with 0.1 M HCl (3 times 25 mL), sat. aq. NaHCO.sub.3 (25 mL), a 3:5 v/v mixture of brine and sat. aq. NaHCO.sub.3 (2 times 40 mL), and brine (30 mL). The organics were dried (MgSO.sub.4) and the voaltiles removed in vacuo. The intermediate was purified by flash chromatography (methanol/DCM) and then purified by RP-HPLC to give a colourless oil. The oil was dissolved in DCM (0.5 mL) and TFA (0.5 mL) was added. After stirring at RT for 55 min, the volatiles were removed under a stream of nitrogen. The residues were diluted with acetonitrile/H.sub.2O 1:1+0.1% TFA (2 mL)+0.1% TFA and water (4 mL). The mixture was lyophilized to give a colourless oil.

[0590] Yield: 136 mg (52%, TFA salt)

[0591] MS: m/z 288.19=[M+H].sup.+, (calculated=288.19).

Example 45: Synthesis of Compound 14d

[0592] ##STR00097##

[0593] Compound 14b (251 mg, 0.63 mmol) was dissolved in DMF (2.30 mL) and N-Boc-Sar-OH (121 mg, 0.64 mmol) and PyBOP (358 mg; 0.69 mmol) were added followed by DIPEA (326 μL, 1.87 mmol) to form a light-yellow solution. After stirring at RT for 90 min, the mixture was diluted with ethyl acetate (50 mL) and washed with 0.1 M HCl (3 times 25 mL), sat. aq. NaHCO.sub.3 (25 mL), a 3:5 v/v mixture of brine and sat. aq. NaHCO.sub.3 (2 times 40 mL), and brine (30 mL). The organics were dried over MgSO.sub.4 and the voaltiles removed in vacuo. The intermediate was purified by flash chromatography (methanol/DCM) to give a colourless oil. The oil was dissolved in DCM (0.5 mL) and the solution treated with TFA (0.5 mL). After stirring at RT for 55 min, the volatiles were removed under a stream of nitrogen. The residues were diluted with 1:1 acetonitrile/H.sub.2O+0.1% TFA (2 mL)+0.1% TFA and water (4 mL). The mixture lyophilized to give a colourless oil.

[0594] Yield: 129 mg (51%, TFA salt)

[0595] MS: m/z 274.18=[M+H].sup.+, (calculated=274.17).

Example 46: Synthesis of Compound 14e

[0596] ##STR00098##

[0597] 14e was synthesized using solid-phase synthesis following the general protocol using Fmoc-trans-1,4-ACHC-OH and Fmoc-Pro-OH as building blocks.

Example 47: Synthesis of Compound 14f

[0598] ##STR00099##

[0599] 14f was synthesized using solid-phase synthesis following the general protocol using Fmoc-Ahx-OH, (S)-Fmoc-4-aminopentanoic acid, and Fmoc-N-Methyl-Ala-OH as building blocks.

Example 48: Synthesis of Compound 14g

[0600] ##STR00100##

[0601] 14g was synthesized using solid-phase synthesis following the general protocol using Fmoc-Ahx-OH, Fmoc-trans-1,4-ACHC-OH, and Fmoc-Sar-OH as building blocks.

Example 49: Synthesis of Compound 14h

[0602] ##STR00101##

[0603] 14h was synthesized using solid-phase synthesis following the general protocol using Fmoc-N-Methyl-β-Ala-OH, (S)-Fmoc-4-aminopentanoic acid, and Fmoc-N-Methyl-Ala-OH as building blocks.

Example 50: Synthesis of Compound 14i

[0604] ##STR00102##

[0605] 14i was synthesized using solid-phase synthesis following the general protocol using Fmoc-Ahx-OH, (S)-Fmoc-4-aminopentanoic acid, and Fmoc-N-Ethyl-Gly-OH as building blocks.

Example 51: Synthesis of 15a

[0606] ##STR00103##

[0607] 14a (213 mg, 0.64 mmol) was dissolved in 500 μL of DMF and DIPEA (247 μL, 1.42 mmol) was added. A suspension of 3 (162 mg, 0.28 mmol, in 2.0 mL DMF) was added. After 2 h TFA (110 μl, 1.44 mmol) was added and the product purified by RP-HPLC.

[0608] Yield: 111 mg (54%, TFA salt)

[0609] MS: m/z 629.20=[M+H].sup.+, (calculated=629.25).

Example 52: Synthesis of 15b

[0610] ##STR00104##

[0611] Compound 14c (136 mg, 0.338 mmol) was dissolved in DMF (0.25 mL) and DIPEA (147 μL, 0.845 mmol) was added. To the stirred colourless solution was added 3 (100 mg, 0.169 mmol) in DMF (1.23 mL) and the mixture immediately turned clear yellow. The mixture was stirred at RT for 105 min then TFA (65 μL, 0.845 mmol) was added. The product was purified by RP-HPLC to give a yellow solid.

[0612] Yield: 100 mg (72%, TFA salt)

[0613] MS: m/z 700.24=[M+H].sup.+, (calculated=700.29).

Example 53: Synthesis of 15c

[0614] ##STR00105##

[0615] Compound 14d (129 mg, 0.333 mmol) was dissolved in DMF (0.25 mL) and DIPEA (145 μL, 0.83 mmol) was added. To the stirred colourless solution was added 3 (98 mg, 0.169 mmol) in DMF (1.21 mL) and the mixture immediately turned clear yellow. The mixture was stirred at RT for 105 min then TFA (65 μL, 0.845 mmol) was added. The product was purified by RP-HPLC to give a yellow solid.

[0616] Yield: 101 mg (75%, TFA salt)

[0617] MS: m/z 686.19=[M+H].sup.+, (calculated=686.27).

Example 54: Synthesis of 15d-h

[0618] ##STR00106## ##STR00107##

[0619] The conjugates 15d-h were prepared from their respective resin-loaded Fmoc-protected amines 14e-i, which were treated with 96:2:2 DMF/piperidine/DBU (5 ml) and shaken for 15 min at RT. The filtrate was drained and the procedure repeated twice before washing of the resin with DMF (5 times). The resin was then treated with a suspension of 3 in DMF and DIPEA. The mixture was shaken at RT for between 90 and 200 min before being washed with DMF (5 times) and DCM (5 times). The resin was treated with 1:9 TFA/DCM and shaken at RT for 10 min. The filtrate was collected and this was repeated at least once. The volatiles were removed from the combined filtrates in vacuo to give the acid.

[0620] 15d: 14e: 493 mg, 0.453 mmol, 3: 266 mg, 0.453 mmol, DMF: 3.5 mL, DIPEA: 485 μL, 2.72 mmol.

[0621] Yield: 331 mg (95%, TFA salt). MS: m/z=653.29 [M+H].sup.+, (calculated=653.25).

[0622] 15e: 14f: 195 mg, 0.16 mmol, 3: 119 mg, 0.20 mmol, DMF: 1.5 mL, DIPEA: 173 μL, 0.97 mmol.

[0623] Yield: 136 mg (quant., TFA salt). MS: m/z=728.36 [M+H].sup.+, (calculated=728.32).

[0624] 15f: 14g: 312 mg, 0.26 mmol, 3:188 mg, 0.32 mmol, DMF: 2.3 mL, DIPEA: 275 μL, 1.54 mmol.

[0625] Yield: 274 mg (quant., TFA salt). MS: m/z=740.34 [M+H].sup.+, (calculated=740.32).

[0626] 15g: 14h: 170 mg, 0.15 mmol, 3: 108 mg, 0.18 mmol, DMF: 1.3 mL DIPEA: 158 μL, 0.88 mmol.

[0627] Yield: 124 mg (quant., TFA salt). MS: m/z=700.32 [M+H].sup.+, (calculated=700.29).

[0628] 15h: 14i: 201 mg, 0.17 mmol 3: 123 mg, 0.21 mmol, DMF: 1.5 mL DIPEA: 0.18 mL, 1.00 mmol.

[0629] Yield: 155 mg (quant., TFA salt). MS: m/z=728.34 [M+H].sup.+, (calculated=728.32).

Example 55: Synthesis of Compounds 16a-f

[0630] ##STR00108## ##STR00109##

[0631] The respective acid selected from 15a-e, h was dissolved in DCM and Bis(pentafluorophenyl) carbonate was added. DIPEA was added and the reaction stirred at RT. Once the reaction was complete it was quenched with TFA and the product purified by flash chromatography (THF/ethyl acetate).

[0632] 16a: DCM: 4.0 mL, Bis(pentafluorophenyl) carbonate: 213 mg, 0.54 mmol, DIPEA: 377 μL, 2.16 mmol, 15d: 331 mg, 0.43 mmol, TFA: 165 μL, 2.16 mmol.

[0633] Yield: 273 mg (68%, TFA salt). MS: m/z 819.34=[M+H].sup.+, (calculated=819.23).

[0634] 16b: DCM: 2.0 mL, Bis(pentafluorophenyl) carbonate: 70 mg, 0.178 mmol, DIPEA: 130 μL, 0.746 mmol, 15a: 111 mg, 0.149 mmol, TFA: 57 μL, 0.746 mmol.

[0635] Yield: 122 mg (90%, TFA salt). MS: m/z 795.25=[M+H].sup.+, (calculated=795.23).

[0636] 16c: DCM: 1.50 mL, Bis(pentafluorophenyl) carbonate: 91 mg, 0.23 mmol, DIPEA: 162 μL, 0.93 mmol, 15e: 156 mg, 0.19 mmol, TFA: 71 μL, 0.93 mmol.

[0637] Yield: 94 mg (50%, TFA salt). MS: m/z 894.30=[M+H].sup.+, (calculated=894.30).

[0638] 16d: DCM: 1.50 mL, Bis(pentafluorophenyl) carbonate: 91 mg, 0.23 mmol, DIPEA: 161 μL, 0.92 mmol, 15h: 155 mg, 0.18 mmol, TFA: 71 μL, 0.92 mmol.

[0639] Yield: 105 mg (56%, TFA salt). MS: m/z 894.31=[M+H].sup.+, (calculated=894.30).

[0640] 16e: DCM: 2.00 mL, Bis(pentafluorophenyl) carbonate: 58 mg, 0.147 mmol, DIPEA: 107 μL, 0.61 mmol, 15b: 100 mg, 0.122 mmol, TFA: 47 μL, 0.61 mmol.

[0641] Yield: 77 mg (64%, TFA salt). MS: m/z=866.26 [M+H].sup.+, (calculated=866.27).

[0642] 16f: DCM: 2.00 mL, Bis(pentafluorophenyl) carbonate: 59 mg, 0.151 mmol, DIPEA: 110 μL, 0.63 mmol, 15c: 101 mg, 0.126 mmol, TFA: 48 μL, 0.63 mmol.

[0643] Yield: 96 mg (79%, TFA salt). MS: m/z=852.21 [M+H].sup.+, (calculated=852.26).

Example 56: Synthesis of Compound 16g

[0644] ##STR00110##

[0645] To a solution of 15f (274 mg, 0.32 mmol) in DCM (2.5 mL) was added bis(pentafluorophenyl) carbonate (158 mg, 0.40 mmol) followed by DIPEA (280 μL, 1.60 mmol). Further DCM (2.5 mL) and DIPEA (280 μL, 1.60 mmol) were added to the suspension. acetonitrile (1 mL) and DMF (2 mL) were added. The suspension was stirred at RT for 1 d. The mixture was filtered, and the precipitate washed with DCM. The combined filtrates were washed with water, dried (Na.sub.2SO.sub.4), filtered and concentrated in vacuo. The concentrate was diluted with DCM before addition of TFA (245 μL, 3.18 mmol) and the product purified by flash chromatography (THF/ethyl acetate).

[0646] Yield: 66 mg (20%, TFA salt)

[0647] MS: m/z 906.41=[M+H].sup.+, (calculated=906.30).

Example 57: Synthesis of Compound 16h

[0648] ##STR00111##

[0649] To a solution of 15g (124 mg, 0.15 mmol) in DCM (1.5 mL) was added Bis(pentafluorophenyl) carbonate (75 mg, 0.19 mmol) followed by DIPEA (133 μL, 0.76 mmol). After stirring at RT for 3 h further Bis(pentafluorophenyl) carbonate (19 mg, 0.05 mmol) was added, and after a further 1 h DIPEA (65 μL, 0.37 mmol) was added. The mixture was left to stir at RT for another 18 h. The product was purified directly by flash chromatography (THF/ethyl acetate).

[0650] Yield: 24 mg (16%, TFA salt)

[0651] MS: m/z 866.30=[M+H].sup.+, (calculated=866.27).

Example 58: Synthesis of Compounds 17a-q

[0652] Various hydrogels (amine content of 0.564-0.934 mmol/g) were reacted with Axitinib-linker-conjugates according to the following scheme:

##STR00112## ##STR00113## ##STR00114## ##STR00115##

[0653] The hydrogel was swollen in 1% DIPEA in DMF in a syringe reactor containing a PE frit. The syringe reactor was 3 times filled, shaken for 1 min and drained. A PFP-ester selected from 9e-f or 16a-h was dissolved in DMF and DIPEA was added. The solution was drawn into the syringe containing the hydrogel. The syringe was shaken for longer than 16 h at RT. The syringe was drained, and the hydrogel was washed several times with DMF, then water, then pH 5.5 20 mM sodium succinate aqueous buffer. A hydrogel suspension in pH 5.5 aqueous buffer was obtained. The proportion of amines from the hydrogel that were conjugated was determined by comparing the determined drug content of the product with the amine content of the starting amine hydrogels.

[0654] 17a: HG-6: 21 mg, DIPEA: 12.1 μL, 16a: 29 mg

[0655] yield: suspension, 94% Axitinib loading, 17.93 mg/mL axitinib in hydrogel suspension.

[0656] 17b: HG-12: 20 mg, DIPEA: 10.8 μL, 16a: 27 mg

[0657] yield: suspension, 69% Axitinib loading, 11.69 mg/mL axitinib in hydrogel suspension.

[0658] 17c: HG-11: 19 mg, DIPEA: 9.3 μL, 16b: 17 mg

[0659] yield: suspension, 100% Axitinib loading, 16.24 mg/mL axitinib in hydrogel suspension.

[0660] 17d: HG-8: 20 mg, DIPEA: 11.7 μL, 16b: 22 mg

[0661] yield: suspension, 95% Axitinib loading, 16.10 mg/mL axitinib in hydrogel suspension.

[0662] 17e: HG-13: 16 mg, DIPEA: 9.5 μL, 16b: 18 mg

[0663] yield: suspension, 97% Axitinib loading, 18.63 mg/mL axitinib in hydrogel suspension.

[0664] 17f: HG-11: 19 mg, DIPEA: 9.5 μL, 16c: 20 mg

[0665] yield: suspension, 100% Axitinib loading, 16.43 mg/mL axitinib in hydrogel suspension.

[0666] 17g: HG-11: 20 mg, DIPEA: 10.0 μL, 16g: 21 mg

[0667] yield: suspension, 95% Axitnib loading, 14.03 mg/mL axitinib in hydrogel suspension.

[0668] 17h: HG-11: 20 mg, DIPEA: 9.9 μL, 16h: 24 mg

[0669] yield: suspension, 84% Axintib loading, 11.17 mg/mL axitinib in hydrogel suspension.

[0670] 17i: HG-11: 20 mg, DIPEA: 9.9 μL, 16d: 20 mg

[0671] yield: suspension, 94% Axitinib loading, 14.66 mg/mL axitinib in hydrogel suspension.

[0672] 17j: HG-8: 20 mg, DIPEA: 11.8 μL, 16d: 25 mg

[0673] yield: suspension, 96% Axitinib loading, 15.72 mg/mL axitinib in hydrogel suspension.

[0674] 17k: HG-13: 15 mg, DIPEA: 9.1 μL, 16d: 19 mg

[0675] yield: suspension, 100% Axitinib loading, 19.46 mg/mL axitinib in hydrogel suspension.

[0676] 17l: HG-4: 15 mg, DIPEA: 8.5 μL, 9e: 15 mg

[0677] yield: suspension, 98% Axitinib loading, 18.27 mg/mL axitinib in hydrogel suspension.

[0678] 17m: HG-11: 21 mg, DIPEA: 10.2 μL, 9e: 19 mg

[0679] yield: suspension, 100% Axitinib loading, 15.60 mg/mL axitinib in hydrogel suspension.

[0680] 17n: HG-14: 20 mg, DIPEA: 16.2 μL, 9e: 32 mg

[0681] yield: suspension, 81% Axitinib loading, 21.15 mg/mL axitinib in hydrogel suspension.

[0682] 17o: HG-13: 16 mg, DIPEA: 9.4 μL, 16e: 19 mg

[0683] yield: suspension, 99% Axitinib loading, 19.28 mg/mL axitinib in hydrogel suspension.

[0684] 17p: HG-13: 16 mg, DIPEA: 9.7 μL, 16f: 19 mg

[0685] yield: suspension, 100% Axitinib loading, 20.66 mg/mL axitinib in hydrogel suspension.

[0686] 17q: HG-15: 20 mg, DIPEA: 10.6 μL, 9f: 21 mg

[0687] yield: suspension, 93% Axitinib loading, 15.75 mg/mL axitinib in hydrogel suspension.

Example 59: In Vitro Release Kinetics

[0688] The cleavage rate of the reversible bond from conjugates 9a-d, 13a-e and 17b-q was monitored at 37° C. in aqueous buffer (condition A: pH 7.4 60 mM sodium phosphate, 1% acetonitrile, B: pH 7.4 48 mM sodium phosphate, 20% acetonitrile, 0.1% Pluronic F68, C: pH 7.4 48 mM sodium phosphate with 16 mM L-Methionine 2.4 mM EDTA, 0.1% pluronic and 20% acetonitrile, D: pH 7.0 48 mM sodium phosphate with 16 mM L-Methionine 2.4 mM EDTA, 0.1% pluronic and 20% acetonitrile, E: pH 7.4 60 mM sodium phosphate, F: pH 7.4 48 mM sodium phosphate, 20% acetonitrile). For soluble examples disappearance of the conjugate was determined by LCMS (UV detection) and fitted with curve fitting software to obtain the half-life of the release. For insoluble examples (hydrogels) the increase in released axitinib in the supernatant was determined by LCMS (UV detection) and used as input for the curve fitting software to obtain the half-life of the release. Release rates at pH 7.4 for conjugates only incubated at pH 7.0 are estimated to increase by a factor of 2 to 3.

TABLE-US-00002 Compound t.sub.1/2 pH Buffer Released product  9a* 4.0 d  7.4 F axitinib  9b* 11.5 d   7.4 F axitinib  9c* 47 d 7.4 F axitinib  9d* 4.6 d  7.4 F axitinib 13a* 4.2 d  7.4 F 1H-indazole-3-carboxylic acid 13b* 3.6 d  7.4 F 1H-indazole-3-carboxylic acid 13c* 6.9 d  7.4 F 1H-indazole-3-carboxylic acid 13d* 3.2 d  7.4 F 1H-indazole-3-carboxylic acid 13e* 4.5 d  7.4 F 1H-indazole-3-carboxylic acid 17b 107 d  7.0 D axitinib 17b 181 d  7.4 C axitinib 17c 28 d 7.0 D axitinib 17c 12 d 7.4 C axitinib 17d 26 d 7.0 D axitinib 17e 30 d 7.0 D axitinib 17f 49 d 7.0 D axitinib 17f 20 d 7.4 C axitinib 17g 17 d 7.0 D axitinib 17g  7 d 7.4 C axitinib 17h 51 d 7.0 D axitinib 17h 21 d 7.4 C axitinib 17i 27 d 7.0 D axitinib 17i 12 d 7.4 C axitinib 17j 24 d 7.0 D axitinib 17k 30 d 7.0 D axitinib 171 17 d 7.0 D axitinib 17m 16 d 7.0 D axitinib 17m  7 d 7.4 C axitinib 17n  8 d 7.4 B axitinib 17o 43 d 7.0 D axitinib 17p 15 d 7.0 D axitinib 17q 38 d 7.4 C axitinib

[0689] The compounds marked with “*” are not in accordance with the present invention as they were for efficiency reasons not linked to a moiety Z. Nevertheless, they show the release half-lives of such moieties -L.sup.1-.

Example 60: Synthesis of Compounds 17r-t

[0690] The hydrogel HG-17 was reacted with Axitinib-linker-conjugates according to the following scheme:

##STR00116##

[0691] The hydrogel was swollen in 1% DIPEA in DMF in a syringe reactor containing a PE frit. The syringe reactor was 3 times filled, shaken for 1 min and drained. A PFP-ester selected from 16b or 16c was dissolved in DMF and DIPEA was added. The solution was drawn into the syringe containing the hydrogel. The syringe was shaken for longer than 16 h at RT. The syringe was drained, and the hydrogel was washed several times with DMF, then water, then pH 5.5 buffer (20 mM sodium succinate, 77 g/l trehalose dihydrate, 0.2% Pluronic F-68). A hydrogel suspension in pH 5.5 aqueous buffer was obtained. The proportion of amines from the hydrogel that were conjugated was determined by comparing the determined drug content of the product with the amine content of the starting amine hydrogels.

[0692] 17r: HG-17: 24 mg, DIPEA: 17.8 μL, 16b: 15 mg

[0693] yield: suspension, 73% Axitinib loading, 17.63 mg/mL axitinib in hydrogel suspension.

[0694] 17s: HG-17: 24 mg, DIPEA: 18.1 μL, 16b: 20 mg

[0695] yield: suspension, 94% Axitinib loading, 22.40 mg/mL axitinib in hydrogel suspension.

[0696] 17t: HG-17: 24 mg, DIPEA: 18.2 μL, 16c: 17 mg

[0697] yield: suspension, 62% Axitinib loading, 14.87 mg/mL axitinib in hydrogel suspension.

Example 61: In Vitro Release Kinetics

[0698] The cleavage rate of the reversible bond from conjugates 17r-t was monitored at 37° C. in pH 7.0 48 mM sodium phosphate buffer with 16 mM L-Methionine 2.4 mM EDTA, 0.1% pluronic and 20% acetonitrile. The increase in released axitinib in the supernatant was determined by LCMS (UV detection) and used as input for the curve fitting software to obtain the half-life of the release. The release rates at pH 7.4 for these conjugates are estimated to be faster by a factor of 2 to 3.

TABLE-US-00003 Compound t.sub.1/2 Released product 17r 20 d axitinib 17s 34 d axitinib 17t 31 d axitinib

Example 62

[0699] ##STR00117##

[0700] For 17u, a PEG based amino hydrogel is synthesized as described in example 3 of WO2011/012715A1 using a backbone synthesized using Boc-L-Lys(Boc)-OH as described in example 1 of WO2011/012715A1, and a 2 kDa PEG based crosslinker that is synthesized using adipic acid as described in example 2 of WO2011/012715A1. The hydrogel is then modified with lysine using Fmoc-L-Lys(Fmoc)-OH as described in example 5 of WO2011/042450A1 to give a hydrogel with an amine content of 0.700 mmol/g. The hydrogel is swollen in 1% DIPEA in DMF in a syringe reactor fitted with a frit and washed three times with a 1% DIPEA/DMF solution. 16b (1.8 eq. per hydrogel amine) is dissolved in DMF and DIPEA (5.0 eq.) is added. The solution is drawn into the hydrogel-containing reactor and shaken for 16 h at rt. The syringe is drained, the hydrogel washed several times with DMF, washed several times with water, then washed several times with pH 5.5 20 mM sodium succinate aqueous buffer. A hydrogel suspension in pH 5.5 aqueous buffer where the Axitinib loading is greater than 95% is obtained.

[0701] The hydrogel 17v is prepared as described for 17u, but Boc-D-Lys(Boc)-OH is used for the backbone synthesis instead of Boc-L-Lys(Boc)-OH, and Fmoc-D-Lys(Fmoc)-OH instead of Fmoc-L-Lys(Fmoc)-OH is used for the lysine modification.

Example 63: Synthesis of Compound 18

[0702] ##STR00118##

[0703] 14a (20 mg, 61 μmol) was dissolved in THF (0.5 mL). DIPEA (26 μL, 151 μmol) was added and a precipitate formed. The precipitate was finely distributed using sonication and stirring to form a milky suspension. 1,1′-carbonyldiimidazole (9.8 mg, 61 μmol) was dissolved in 0.15 ml THF and added to the suspension with stirring. After 40 min the reaction was quenched with acetic acid (30 μl) and diluted with water to 1 ml total volume. The product was purified by RP-HPLC to give 18.

[0704] Yield: 0.8 mg (4%)

[0705] MS: m/z 311.08=[M+H].sup.+, (calculated=311.17).

Example 64: Synthesis of Compound 19

[0706] ##STR00119##

[0707] A solution of methyl 1H-benzo[d]imidazole-5-carboxylate (25 mg, 117.6 μmol) in THF (500 μl) was cooled to 0° C. and 1-methylimidazole (19.2 μl, 241 μmol) was added. A solution of 4-nitrophenyl chloroformate (24.9 mg, 123.5 μmol) in THF (250 μl) was added dropwise. DMF (500 μl) was added to the reaction mixture to enhance the solubility of a formed precipitate. The mixture was allowed to warm up to ambient temperature in the cooling bath slowly. After 1.5 h additional 1-methylimidazole (19.2 μl, 241 μmol) was added and the reaction mixture was stirred at ambient temperature for approx. 17 h. The reaction mixture is cooled to 0° C. and a solution of 4-nitrophenyl chloroformate (12.5 mg, 62 μmol) in THF (200 μl) was added dropwise. The reaction mixture was stirred at 0° C. for 75 min, then additional 4-nitrophenyl chloroformate (12.5 mg, 62 μmol) in THF (200 μl) was added. The reaction mixture was stirred for 53 min at 0° C., diluted with ethylacetate (ca. 15 ml), washed with 0.1 M HCl (3×5 ml) and brine (ca. 10 ml). The organic layer was dried with Na.sub.2SO.sub.4, filtrated and concentrated under reduced pressure. 19 was purified using flash chromatography.

[0708] Yield: 35 mg (87.2%, mixture of benzimidazole regioisomers)

[0709] MS: m/z 342.06=[M+H].sup.+, (calculated=342.07).

Example 65: Synthesis of Compound 20

[0710] ##STR00120##

[0711] To a solution of compound 19 (11.5 mg, 30.3 μmol) in DMF (314 μl) were added DIPEA (21.2 μl, 121.3 μmol) and compound 14a (11.2 mg, 33.4 μmol) successively and the reaction mixture was stirred at ambient temperature for 3 h. The reaction was quenched by addition of TFA (9.3 μl, 121.3 μmol) and the reaction purified by RP-HPLC.

[0712] Yield: 2.2 mg (17.3%, mixture of benzimidazole regioisomers)

[0713] MS: m/z 419.18=[M+H].sup.+, (calculated=419.19).

Example 66: Synthesis of Compound 21

[0714] ##STR00121##

[0715] A suspension of NaH (60% in mineral oil, 8.3 mg, 207.5 μmol) in THF (250 μl) was cooled to 0° C. and a solution of tert-butyl 1H-indole-5-carboxylate (15 mg, 69 μmol) in THF (400 μl) was added dropwise. After complete addition the mixture was stirred for 1 h at 0° C. This mixture was added to a cooled solution of 4-nitrophenyl chloroformate (34.8 mg, 172.6 μmol) in THF (500 μl). Additional THF (250 μl) was used to flush the flask and was added to the 4-nitrophenyl chloroformate solution. After 1.5 h the cooling bath was removed, and the mixture was stirred at ambient temperature. After 30 min 4-nitrophenyl chloroformate (69.6 mg, 346.8 μmol) was added in one portion. After 3 h the reaction mixture was diluted with ethyl acetate (15 ml), washed with HCl (0.1 M, 3×5 ml), brine (5 ml), dried with Na.sub.2SO.sub.4, filtrated, and concentrated under reduced pressure. 21 was purified using flash chromatography.

[0716] Yield: 16 mg (60.6%)

[0717] MS: m/z 327.04=[M -tBu+2H].sup.+, (calculated=327.06).

Example 67: Synthesis of Compound 22

[0718] ##STR00122##

[0719] To a solution of compound 21 (8 mg, 18.8 μmol) in DMF (250 μl) were added DIPEA (13.1 μl, 75.3 μmol) and N,N,N′-trimethylethylenediamine (2.7 μl, 20.7 μmol) successively. The mixture was stirred at ambient temperature for 1 h 45 min before being quenched by addition of TFA (5.6 μl, 75.3 μmol). 22 was purified using RP-HPLC.

[0720] Yield: 4.6 mg (70.7%, TFA salt)

[0721] MS: m/z 346.18=[M+H].sup.+, (calculated=346.21).

Example 68: Synthesis of Compound 23

[0722] ##STR00123##

[0723] To a solution of compound 22 (1.15 mg, 3.3 μmol) in DCM (250 μl) was added TFA (250 μl) and the mixture was stirred at ambient temperature for 25 min. The reaction was diluted with toluene and concentrated under reduced pressure. The obtained material was used directly in the in vitro release kinetics.

[0724] MS: m/z 290.15=[M+H].sup.+, (calculated=290.15).

Example 69: In Vitro Release Kinetics

[0725] The cleavage rate of the reversible bond from conjugates 18, 20, 23 was monitored at pH 7.4 and 37° C. in aqueous buffer (pH 7.4 48 mM sodium phosphate, 20% acetonitrile). Disappearance of the conjugate was determined by LCMS (UV detection) and fitted with curve fitting software to obtain the half-life of the release.

TABLE-US-00004 Compound t.sub.1/2 Released product 18 1.7 d imidazole 20 1.8 d methyl 1H-benzo[d]imidazole-5-carboxylate 23  31 d indole-5-carboxylate

Abbreviations

[0726] ACHC aminocyclohexane carboxylic acid [0727] Ahx 6-aminohexanoic acid [0728] aq. aqueous [0729] Asp aspartate [0730] Bn benzyl [0731] Boc tert-butyloxycarbonyl [0732] COMU (1-Cyano-2-ethoxy-2-oxoethylidenaminooxy)dimethylamino-morpholino-carbenium hexafluorophosphate [0733] DBU 1,8-diazabicyclo (5.4.0)undec-7-ene [0734] DCM dichloromethane [0735] DIC N,N′-diisopropylcarbodiimide, [0736] DIPEA diisopropylethylamine [0737] DMAP dimethylaminopyridine [0738] DMF dimethylformamide [0739] eq. equivalent [0740] EDC 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide [0741] Fmoc fluorenylmethyloxycarbonyl [0742] HATU O-(7-Azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium-hexafluorphosphat [0743] HFIP 1,1,1,3,3,3-hexafluoroisopropanol [0744] HOBt 1-hydroxybenzotriazole [0745] HPLC high performance liquid chromatography [0746] LC liquid chromatography [0747] LCMS liquid chromatography mass spectrometry [0748] LPLC low pressure liquid chromatography [0749] MeOH methanol [0750] MS mass spectrometry [0751] PEG polyethylene glycol [0752] PFP pentafluorophenyl [0753] PNP para-nitrophenyl [0754] PyBOP benzotriazol-1-yl-oxytripyrrolidinophosphonium hexafluorophosphate [0755] RP reversed phase [0756] RT room temperature [0757] Sar sarcosine [0758] sat. saturated [0759] tBu and t-Bu tert-butyl [0760] TES triethylsilane [0761] TEA triethylamine [0762] TFA trifluoroacetic acid [0763] THF tetrahydrofurane [0764] Thr threonine [0765] Tmob 2,4,6-trimethoxybenzyl [0766] Trt trityl [0767] UPLC ultra performance liquid chromatography [0768] UPLC-MS ultra performance liquid chromatography coupled to mass spectrometry