Boron-based prodrug strategy for increased bioavailability and lower-dosage requirements for drug molecules containing at least one phenol (or aromatic hydroxyl) group

Abstract

Boron-based prodrugs of phenol- or aromatic hydroxyl group-containing therapeutic molecules (original drugs), uses thereof, and methods of making the same, are provided for achieving, for example, improved bioavailability, prolonged retention (e.g., in a circulatory system) and, in particular, significantly lowered therapeutically effective dosage in order to reduce adverse effects while maintaining the desired therapeutic effects of the original drugs.

Claims

1. A compound of Formula 29: ##STR00120## wherein R is selected from the group consisting of: ##STR00121## KF.sub.3B; (HO).sub.2B; and NaF.sub.3B; and wherein the boron atom is the point of attachment in each R variable substituent, and any salts thereof.

2. The compound of claim 1, wherein R is ##STR00122##

3. The compound of claim 1, wherein R is: (HO).sub.2B.

4. A pharmaceutical composition comprising the compound of claim 1.

5. A method of treating breast cancer in a mammal in need thereof, the method comprising administering to said mammal the compound of claim 1 in an amount that is therapeutically effective for said treatment.

6. A method of downregulating an estrogen receptor in a mammal in need thereof, the method comprising administering to said mammal the compound of claim 1 in an amount that is therapeutically effective for said downregulation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a further understanding of the nature, objects, and advantages of the present disclosure, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements.

(2) FIG. 1 shows the general synthetic scheme for preparation of boron-based prodrugs from various drug molecules containing at least one aromatic hydroxyl group.

(3) FIG. 2 shows the facile conversion of boron-acetaminophen prodrug to the original drugs under physiological conditions.

(4) FIG. 3 shows the pharmacokinetics of boron-acetaminophen in mouse plasma.

(5) FIG. 4 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of fulvestrant.

(6) FIG. 5 shows the facile conversion of boron-fulvestrant prodrug to the original drugs under physiological conditions.

(7) FIG. 6 shows the pharmacokinetics of boron-fulvestrant in mouse plasma.

(8) FIG. 7 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of raloxifene.

(9) FIG. 8 shows the pharmacokinetic profile of boron-raloxifene in mouse plasma.

(10) FIG. 9 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of lasofoxifene.

(11) FIG. 10 shows the pharmacokinetic profile boron-lasofoxifene in mouse plasma.

(12) FIG. 11 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of bazedoxifene.

(13) FIG. 12 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of SN-38.

(14) FIG. 13 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of fenretinide.

(15) FIG. 14 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of daidzein.

(16) FIG. 15 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of resveratrol.

(17) FIG. 16 shows the synthetic scheme for preparation of the pinacolyl boronate ester prodrug of equol.

DETAILED DESCRIPTION

(18) Before the subject disclosure is further described, it is to be understood that the disclosure is not limited to the particular embodiments of the disclosure described below, as variations of the particular embodiments may be made and still fall within the scope of the appended claims. It is also to be understood that the terminology employed is for the purpose of describing particular embodiments, and is not intended to be limiting. Instead, the scope of the present disclosure will be established by the appended claims.

(19) In this specification and the appended claims, the singular forms a, an, and the include plural reference unless the context clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs.

(20) The subject disclosure features, in one aspect, the synthesis of boron-based prodrugs of various existing therapeutic drug molecules by modifying the phenolic structure in them. To determine whether these prodrugs have enhanced bioavailability in vivo, pharmacokinetic studies were performed in which selected boron-prodrugs were orally administered to mice as a single dose at 5 mg/kg and the drug concentrations in mouse blood were monitored over a period of 24 hours.

(21) As used herein, the term minimize or reduce, or derivatives thereof, include a complete or partial inhibition of a specified biological effect (which is apparent from the context in which the terms minimize or reduce are used).

(22) Examples of existing original drugs that can utilize the boron-prodrug platform where R is

(23) ##STR00004##
or KF.sub.3B, (HO).sub.2B, NaF.sub.3B, wherein the R substituent point of attachment is on the boron atom, are provided by Formulas 1 through 57 of Table 1, along with the corresponding original drugs.

(24) TABLE-US-00001 TABLE 1 Original Drug Molecular Structure of Examples of Pinacolyl Boronate Molecule Original Drug Ester-prodrug Structure Aceta- minophen Acolbifene Amo- diaquine 0 Amoxi- cillin Amrubicin Apo- morphine Arzoxifene Baze- doxifene 0 Bupre- norphine Carbidopa Cefadroxil Cefo- perazone Cefprozil 0 Curcumin Daidzein Dano- rubicin Demeclo- cycline Desvenla- faxine 0 Dex- trorphan (DXO) Dolute- gravir Doxo- rubicin Doxy- cycline Droloxi- fene 0 Equol Fenre- tinide Fidaxo- micin Forme- stane For- moterol 0 Fulves- trant Labetalol Laso- foxifene Levodopa Levoxyl (L- thyroxine) 0 Meloxi- cam Methyl- dopa Mino- cycline Myco- phenolic acid Nelfina- vir 0 Niclo- samide Nonabine Nore- pine- phrine Oxy- tetra- cycline Platensi- mycin 0 Raloxi- fene Ralte- gravir Resvera- trol Rifabutin Rifam- picin 00 Rifa- pentine 01 02 Salbu- tamol (Albu- terol) 03 04 Sero- tonin 05 06 SN-38 07 08 Sulfa- salazine 09 0 Tetra- cycline Tol- terodine (Detrol) Tra- bectedin Vapre- otide (Sanvar)

(25) Preferably, R is

(26) ##STR00119##

(27) Also provided is the use of at least one compound of Formulas 1 through 57 for treatment of a disease or symptom that is treated or treatable by said compound in which said R is OH, in a mammal in need thereof.

(28) Also provided is a compound of Formulas 1 through 57 for use as a medicament, for use in the treatment of cancer in a mammal in need thereof, for use in providing analgesia to or reducing inflammation in a mammal in need thereof, for modulating an estrogen receptor, or for use in treating a bacterial, viral, fungal, or mycoplasma infection in a mammal in need thereof.

(29) In an embodiment, disease or symptom is selected from the group consisting of: a bacterial, viral, fungal, or mycoplasma infection; cancer; ulcer; Parkinson's disease; tuberculosis; leprosy; brucellosis; opioid addiction; arthritis; osteoarthritis; rheumatoid arthritis; leukemia; depression; cough or common cold; human immunodeficiency virus (HIV); anthrax; asthma; bronchitis; hypothyroidism; hypertension; hypotension; congestive heart failure; graft-versus-host disease; helminth infection; mycobacterium avium complex (MAC) disease; ulcerative colitis; overactive bladder; urinary incontinence; and esophageal variceal bleeding.

(30) A synthetic procedure for preparation of the boronic derivatives of the various pharmaceutically active compounds containing at least one aromatic hydroxyl group involves reaction of the above compounds with trifluoromethanesulfonic anhydride or 1,1,1-trifluoro-N-phenyl-N-((trifluoromethyl)sulfonyl) methanesulfonamide to form the triflate. This reaction uses the solvent of dimethyl formamide (DMF) in the presence of an organic base such as pyridine. The triflate thus formed is allowed to react with bis(pinacolato)diboron in the presence of a catalyst, PdCl.sub.2 (dppf) to form the pinacolyl boronate ester prodrug of the active compound.

(31) For example, boronic derivatives of acetaminophen as prodrug candidates were designed by replacing the hydroxyl group with a boron atom that is linked to various functional groups. A schematic of the synthesis of boron-acetaminophen prodrugs is provided in FIG. 2.

(32) The first step of hydrolysis proceeds rapidly in an aqueous environment, while the second step of hydrolysis is known to require physiological conditions such as liver microsome or plasma where oxidative deboronation catalyzed by P450 enzymes leads to rather complete conversion of the boronic prodrug to the original hydroxyl-containing drug molecule, consistent with previous reports on other boronic acid compounds (Pekol et al., Drug Metab Dispos. 2005; 33(6):771-7.). As illustrated in FIG. 2, boron-acetaminophen in aqueous solution quickly hydrolyzed to form its boronic acid counterpart, where the ratio of boronate ester to the acid intermediate reached 9:1 within 5 hours. Oxidative deboronation under acidic or basic conditions, or in the presence of oxidizing agents such as H.sub.2O.sub.2, leads to the original hydroxyl containing drug molecule.

(33) Boronic derivatives of fulvestrant as prodrug candidates were designed by replacing the hydroxyl group with a boron atom that is linked to various functional groups. A schematic of the synthesis of boron-fulvestrant prodrugs is provided in FIG. 4.

(34) The below Examples will further illustrate the chemical structure of various embodiments of the boron-based prodrug compounds taught herein. Furthermore, the Examples demonstrate the efficacy of various embodiments of the disclosed prodrug compounds. As set forth in the scientific data below, it has been surprisingly found that the disclosed boron-based prodrug compounds exhibit superior bioavailability compared to the parent compounds.

EXAMPLE 1

(35) Pinacolyl Boronate Ester Prodrug of Acetaminophen (FIGS. 2 & 3)

(36) To determine if boron-acetaminophen derivatives have enhanced bioavailability in vivo, pharmacokinetic studies were performed in mice where boron-acetaminophen was orally administered to mice as a single dose at 5 mg/kg and the drug concentrations in mouse blood were monitored over a period of 24 hours.

(37) The boron-containing acetaminophen prodrug showed 5-10 fold increases in the plasma concentrations of acetaminophen, thus reducing the therapeutically effective dose requirement to a level that is much less likely to cause accidental overdose.

(38) The results of these studies are presented in FIG. 3 and demonstrate a significant increase in plasma concentration (bioavailability) of acetaminophen in mice administered boron-acetaminophen compared to mice administered an equal dose of acetaminophen.

EXAMPLE 2

(39) Pinacolyl Boronate Ester Prodrug of Fulvestrant (FIGS. 4-6)

(40) Step 1: To a solution of N-2 (0.80 g) and pyridine (0.24 mL) in DCM (15 mL) was added trifluoromethanesulfonic acid anhydride (0.2 mL) dropwise at 10 C., and the resulting mixture was stirred until the reaction was finished. The reaction was quenched with satd. sodium carbonate solution and extracted with ethyl acetate. The combined organic layer was dried over MgSO.sub.4 and concentrated. The crude was purified by flash column to afford liquid product (0.70 g).

(41) Step 2: The mixture of the triflate of N-2 (0.76 g), bis(pinacolato)diboron (0.378 g), potassium acetate (0.268 g, 9.72 mmol), Pd(OAc).sub.2 (30 mg) and tricyclohexylphosphine (60 mg) in acetonitrile (20 mL) was stirred at 80 C. under N.sub.2 overnight. The solvent was removed under vacuum and the crude was purified by flash chromatography to afford product (0.50 g).

(42) Step 3: To a solution of the pinacolyl boronate ester of N-2 (0.5 g) in MeOH-THF (1:1, 4 mL) was added a solution of KOH (0.132 g) in MeOH (2 mL) slowly at 0 C. The resultant mixture was stirred at room temperature for 4 h. After the reaction solution was neutralized with acetic acid, the solvent was removed under vacuum and the crude was purified to afford liquid product (0.40 g).

(43) Step 4: To a solution of the deacetylated pinacolyl boronate ester of N-2 (0.55 g) in DCM (10 mL) was added mCPBA (0.135 g) at 0 C. The resultant mixture was stirred at 0 C. until the starting material was almost transformed to product completely. The reaction solution was diluted with DCM, then washed with saturated Na.sub.2CO.sub.3 and dried. The solvent was removed under vacuum and the crude was purified to afford solid product (0.42 g). .sup.1H-NMR (CDCl.sub.3, 300 MHz): 7.60 (d, J=7.2 Hz, 1H), 7.55 (s, 1H), 7.33 (d, J=7.2 Hz, 1H), 3.76 (m, 1H), 2.89-2.63 (m, 6H), 2.42-2.14 (m, 7H), 1.93 (d, J=12.3 Hz, 1H), 1.80-1.00 (m, 4H), 0.79 (s, 3H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 143.2, 136.7, 134.9, 132.0, 125.4, 83.6, 82.0, 52.7, 51.0, 46.6, 43.3, 41.7, 38.9, 37.0, 34.3, 33.2, 30.6, 30.0, 29.6, 29.3, 29.2, 28.8, 28.3, 26.9, 25.7, 24.9, 24.8, 22.64, 22.56, 14.6, 11.1. HR-MS (ESI(+)): Calcd for C.sub.38H.sub.59BF.sub.5O.sub.4S (M+H): 717.4147. Found: 717.4160.

(44) To determine if boron-fulvestrant derivatives have enhanced bioavailability in vivo, pharmacokinetic studies were performed in mice where boron-fulvestrant was orally administered to mice as a single dose at 5 mg/kg and the drug concentrations in mouse blood were monitored over a period of 24 hours.

(45) In a period of 24 hours post oral administration of either fulvestrant or boron-fulvestrant, plasma concentration of fulvestrant from orally administered boron-fulvestrant was significantly higher than in mice fed with oral gavage of unmodified fulvestrant.

(46) The results of these studies are presented in FIG. 6 and demonstrate a significant increase in plasma concentration of fulvestrant in mice administered boron-fulvestrant compared to mice administered an equal dose of fulvestrant.

EXAMPLE 3

(47) Pinacolyl Boronate Ester Prodrug of Raloxifene (FIGS. 7 & 8)

(48) Step 1: A solution of trifluoromethanesulfonic anhydride (0.84 g, 0.48 mL, 3.0 mmol) in CH.sub.2Cl.sub.2 (5.0 mL) was added dropwise to a solution of pyridine (0.25 mL, 3.0 mmol) and raloxifene (0.47 g, 1 mmol) in anhydrous CH.sub.2Cl.sub.2 (10 mL) at 0 C. After complete addition, the mixture was warmed to room temperature and allowed to stir for 1 hour. The mixture was then diluted with Et.sub.2O, quenched with 10% aq HCl and washed successively with sat. NaHCO.sub.3 solution and brine. After drying over MgSO.sub.4, the solvent was removed under reduced pressure and the residue was purified by flash column chromatography to give the ditriflates (0.16 g). .sup.1H-NMR (300 MHz, CD.sub.3Cl): 7.86-7.83 (m, 2H), 7.68 (d, J=8.4 Hz, 2H), 7.48 (d, J=8.4 Hz, 2H), 7.33 (dd, J=8.7 and 1.5 Hz, 1H), 7.16 (d, J=8.7 Hz, 2H), 6.77 (d, J=8.4 Hz, 2H), 4.34 (t, J=3.3 Hz, 2H), 3.36 (t, J=3.3 Hz, 2H), 3.10 (m, 4H), 1.92 (m, 4H), 1.62 (m, 2H). .sup.13C-NMR (75 MHz, CD.sub.3Cl): 191.4, 163.5, 149.7, 147.1, 144.8, 139.6, 139.1, 133.1, 132.6, 132.3, 131.0, 129.7, 125.4, 121.8, 118.7 (q, J=323 Hz), 115.1, 114.5, 66.1, 57.5, 55.0, 25.7, 24.0. HR-MS (ESI(+)): Calcd. for C.sub.30H.sub.26F.sub.6NO.sub.8S.sub.3 (M+H): 738.0725. Found: 738.0721.

(49) Step 2: To a 1,4-dioxane solution of the ditriflate (0.15 g, 0.20 mmol) were added bis(pinacolato)diboron (0.16 g, 0.60 mmol), PdCl.sub.2(dppf) (0.030 g, 5% mol) and KOAc (0.14 g, 1.4 mmol), and the mixture was irradiated at 120 C. for 1 h under microwave. After the solution was cooled, the dioxane was removed under vacuum. The crude was purified by flash chromatography to afford product (87 mg). .sup.1H-NMR (300 MHz, CD.sub.3Cl): 8.14 (s, 1H), 7.84 (d, J=6.6 Hz, 2H), 7.63 (m, 2H), 7.45 (m, 2H), 7.32 (d, J=6.9 Hz, 2H), 6.81 (d, J=8.1 Hz, 2H), 6.70 (d, J=8.1 Hz, 2H), 5.16 (s, 2H), 4.22 (m, 2H), 3.13 (m, 4H), 2.31 (s, 3H), 1.84 (m, 4H), 1.66 (m, 4H), 1.26 (s, 24H). .sup.13C-NMR (75 MHz, CD.sub.3Cl): 156.8, 139.0, 137.5, 134.7, 131.5, 131.2, 129.8, 128.7, 128.3, 127.4, 126.8, 114.6, 110.4, 109.6, 83.5, 83.4, 83.1, 82.8, 80.3, 75.0, 69.7, 56.0, 55.3, 46.9, 26.8, 25.0, 24.9, 24.5, 24.1, 22.7, 9.5. HR-MS (ESI(+)): Calcd for C.sub.42H.sub.57B.sub.2N.sub.2O.sub.5 (M+H): 691.4454. Found: 691.4460.

(50) To determine if boron-raloxifene derivatives have enhanced bioavailability in vivo, mice were given 5 mg/kg each of raloxifene or boron-raloxifene as a single oral dose and plasma concentration of raloxifene was monitored in each group of mice. Raloxifene concentration in mouse plasma was significantly higher in the group given oral boron-raloxifen than that of mice administered with oral raloxifene (FIG. 8).

EXAMPLE 4

(51) Pinacolyl Boronate Ester Prodrug of Lasofoxifene (FIGS. 9 & 10)

(52) Step 1: A solution of trifluoromethanesulfonic anhydride (0.84 g, 0.48 mL, 3.0 mmol) in CH.sub.2Cl.sub.2 (5.0 mL) was added dropwise to a solution of pyridine (0.25 mL, 3.0 mmol) and lasoxifene (0.41 g, 1 mmol) in anhydrous CH.sub.2Cl.sub.2 (10 mL) at 0 C. After complete addition, the mixture was warmed to room temperature and allowed to stir for 1 hour. The mixture was then diluted with Et.sub.2O, quenched with 10% aq HCl and washed successively with sat. NaHCO.sub.3 solution and brine. After drying over MgSO.sub.4, the solvent was removed under reduced pressure and the residue was purified by flash column chromatography to give the triflates of lasoxifene (0.15 g).

(53) Step 2: To a 1,4-dioxane solution of the triflate of lasoxifene (0.15 g, 0.27 mmol) were added bis(pinacolato)diboron (80 mg, 0.30 mmol), PdCl.sub.2(dppf) (0.015 g, 5% mol) and KOAc (70 mg, 0.7 mmol), and the mixture was irradiated at 120 C. for 1 h under microwave irradiation. After the solution was cooled, the dioxane was removed under vacuum, the crude was purified by flash chromatography to afford product (0.13 g). .sup.1H-NMR (300 MHz, CD.sub.3Cl): 7.74 (s, 1H), 7.53 (d, J=7.2 Hz, 1H), 7.19-7.18 (m, 3H), 6.96 (d, J=7.2 Hz, 1H), 6.83 (m, 2H), 6.52 (d, J=7.8 Hz, 2H), 6.32 (d, J=8.4 Hz, 2H), 4.32-4.30 (m, 3H), 3.42-3.14 (m, 9H), 2.16-2.09 (m, 4H), 1.88 (m, 2H). .sup.13C-NMR (75 MHz, CD.sub.3Cl): 155.6, 143.9, 143.1, 136.0, 135.7, 135.5, 132.0, 131.7, 130.1, 128.1, 127.8, 126.1, 112.9, 64.0, 42.6, 54.2, 51.1, 45.0, 29.6, 24.9, 23.2. HR-MS (ESI(+)): Calcd for C.sub.34H.sub.43BNO.sub.3 (M+H): 524.3336. Found: 524.3329.

(54) To determine if boron-lasofoxifene derivatives have enhanced bioavailability in vivo, mice were given 5 mg/kg each of lasofoxifene or boron-lasofoxifene as a single oral dose and plasma concentration of lasofoxifene was monitored in each group of mice. The systemic bioavailability of lasofoxifene when boron-lasofoxifen was administered was much improved over that afforded by direct oral administration of lasofoxifene (FIG. 10).

EXAMPLE 5

(55) Pinacolyl Boronate Ester-Prodrug of Bazedoxifene (FIG. 11)

(56) Step 1: A solution of trifluoromethanesulfonic anhydride (0.84 g, 0.48 mL, 3.0 mmol) in CH.sub.2Cl.sub.2 (5.0 mL) was added dropwise to a solution of pyridine (0.25 mL, 3.0 mmol) and bazedoxifene (0.47 g, 1 mmol) in anhydrous CH.sub.2Cl.sub.2 (10 mL) at 0 C. After complete addition, the mixture was warmed to room temperature and allowed to stir for 1 hour. The mixture was then diluted with Et.sub.2O, quenched with 10% aq HCl and washed successively with sat. NaHCO.sub.3 and brine. After drying over MgSO.sub.4, the solvent was removed under reduced pressure and the residue was purified by flash column chromatography to give the ditriflates (0.87 g). .sup.1H-NMR (300 MHz, CD.sub.3Cl): 7.50 (d, J=1.8 Hz, 1H), 7.36 (m, 4H), 7.20 (d, J=9.0 Hz, 1H), 7.08 (dd, J=8.7 and 2.1 Hz, 1H), 6.82-6.75 (m, 4H), 5.15 (s, 2H), 4.35 (t, J=3.9 Hz, 2H), 3.64-3.61 (m, 4H), 3.18 (m, 2H), 3.26 (s, 3H), 1.97 (m, 4H), 1.75 (m, 4H). .sup.13C-NMR (75 MHz, CD.sub.3Cl): 156.5, 149.4, 143.6, 137.9, 135.7, 132.2, 131.7, 130.9, 128.9, 127.5, 121.7, 120.2 (q, J=317 Hz), 118.9 (q, J=319 Hz), 118.8 (q, J=321 Hz), 115.6, 114.9, 111.7, 111.1, 111.0, 62.8, 56.7, 56.1, 47.3, 26.3, 23.5, 9.3. HR-MS (ESI(+)): Calcd. for C.sub.32H.sub.33F.sub.6N.sub.2O.sub.7S.sub.2 (M+H): 735.1633. Found: 735.1635.

(57) Step 2: To a 1,4-dioxane solution of the ditriflate (0.15 g, 0.20 mmol) were added bis(pinacolato)diboron (0.16 g, 0.60 mmol), PdCl.sub.2(dppf) (0.030 g, 5% mol) and KOAc (0.14 g, 1.4 mmol), and the mixture was irradiated at 120 C. for 1 h under microwave. After the solution was cooled, the dioxane was removed under vacuum. The crude was purified by flash chromatography to afford product (87 mg). .sup.1H-NMR (300 MHz, CD.sub.3Cl). .sup.13C-NMR (75 MHz, CD.sub.3Cl). HR-MS (ESI(+)): Calcd for C.sub.42H.sub.57B.sub.2N.sub.2O.sub.5 (M+H): 691.4454. Found: 691.4460.

EXAMPLE 6

(58) Pinacolyl Boronate Ester Prodrug of SN-38 (FIG. 12)

(59) Step 1: To the solution of SN-38 (1.2 g, 3.05 mmol) in DMF (30 mL), was added diethyl amine (0.85 mL, 6.12 mmol) and 1,1,1-trifluoro-N-phenyl-N-((trifluoromethyl)sulfonyl) methanesulfonamide (1.64 g, 4.58 mmol). The resultant mixture was stirred at 50 C. for 3 h. The reaction mixture was diluted with DCM and quenched with water. The organic layer was dried over Na.sub.2SO.sub.4 and concentrated. The crude was purified by flash column to afford solid the triflate product (2.1 g).

(60) Step 2: The mixture of the triflate of SN-38 (1.7 g, 3.24 mmol), bis(pinacolato)diboron (1.2 g, 4.86 mmol), potassium acetate (0.875 g, 9.72 mmol), Pd(OAc).sub.2 (40 mg) and tricyclohexylphosphine (100 mg) in acetonitrile (60 mL) was stirred at 80 C. under N.sub.2 for 4 h. The solvent was removed under vacuum and the crude was purified by flash chromatography to afford product (0.80 g). .sup.1H-NMR (CDCl.sub.3, 300 MHz): 8.60 (s, 1H), 8.18-8.17 (m, 2H), 7.68 (s, 1H), 5.76 (d, J=16.2 Hz, 1H), 5.34-5.27 (m, 3H), 3.79 (s, 1H), 3.28 (m, 2H), 1.90 (m, 2H), 1.46-1.42 (m, 15H), 1.04 (t, J=7.5 Hz, 3H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 174.0, 157.7, 152.7, 151.0, 150.2, 147.1, 146.5, 135.0, 131.2, 129.7, 126.8, 126.3, 118.6, 98.2, 84.4, 72.8, 66.4, 49.5, 31.6, 24.9, 23.0, 14.4, 7.8. HR-MS (ESI(+)): Calcd. for C.sub.28H.sub.32BN.sub.2O.sub.6 (M+H): 503.2353. Found: 503.2357.

EXAMPLE 7

(61) Pinacolyl Boronate Ester Prodrug of Fenretinide (FIG. 13)

(62) The mixture of retinoic acid (0.5 g, 1.6 mmol), 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)aniline (0.36 g, 1.6 mmol), EDCI (0.36 g, 2.0 mmol) and DMAP (0.2 g, 1.6 mmol) in 20 mL of dichloromethane was stirred at room temperature overnight until the reaction finish completely. The reaction mixture was applied to a silica gel column and eluted with an ethyl acetate/hexane to afford the product (0.12 g) as yellow oil that solidifies on standing. .sup.1H-NMR (CDCl.sub.3, 300 MHz): 7.76 (d, J=7.2 Hz, 2H), 7.58 (d, J=7.2 Hz, 2H), 7.28 (m, 1H), 7.05-6.92 (m, 2H), 6.30-6.12 (m, 2H), 5.80 (s, 1H), 2.43-0.86 (m, 3314). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 165.2, 151.2, 141.0, 139.4, 137.7, 137.3, 135.8, 135.2, 130.7, 130.0, 129.5, 128.6, 121.0, 118.4, 83.7, 39.6, 34.3, 33.1, 29.0, 24.9, 21.7, 19.2, 13.7, 12.9. MS (ESI(+)): 502.2 (M+).

EXAMPLE 8

(63) Pinacolyl Boronate Ester Prodrug of Daizein (FIG. 14)

(64) Step 1: Daidzein (1.27 g, 0.005 mol) was dissolved in DCM (30 mL), then trifluoromethanesulfonic acid anhydride (3.2 g, 0.011 mol, d 1.677, 1.86 mL) and 4-dimethylaminopyridine (1.22 g, 0.01 mol) were added and the resulting mixture was stirred until the reaction was finished. The reaction was quenched with satd. sodium carbonate solution and extracted with ethyl acetate. The combined organic layer was dried over MgSO.sub.4 and concentrated. The crude was purified by flash column to afford solid product (0.40 g). .sup.1H-NMR (CDCl.sub.3, 300 MHz): 8.43 (d, J=8.7 Hz, 1H), 8.08 (s, 1H), 7.66 (d, J=8.7 Hz, 2H), 7.50 (m, 1H), 7.42-7.33 (m, 3H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 174.5, 156.4, 153.7, 152.4, 149.6, 131.4, 130.8, 129.3, 124.5, 124.1, 121.7, 119.1, 118.8 (q, J=319 Hz), 111.6. GC-MS: 518.1 (M+).

(65) Step 2: The triflate (0.26 g, 0.5 mmol), diboron reagent (0.36 g, 3.6 mmol), PdCl.sub.2(dppf) (0.014 g, 0.16 mmol) and potassium acetate (0.24 g, 2.4 mmol) was dissolved in dioxane (3 mL), then the mixture was stirred at 80 C. under microwave irradiation. The solvent was removed under vacuum and the crude purified by flash chromatography to afford product (0.12 g). .sup.1H-NMR (CDCl.sub.3, 300 MHz): 8.29 (d, J=7.8 Hz, 1H), 8.06 (s, 1H), 7.93-7.87 (m, 3H), 7.81 (d, J=7.8 Hz, 1H), 7.60 (d, J=7.8 Hz, 2H), 1.38 (s, 12H), 1.36 (s, 12H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 176.2, 155.6, 153.5, 134.9, 134.8, 130.7, 128.2, 126.3, 125.5, 125.4, 124.5, 84.6, 83.9, 24.90, 24.88. GC-MS: 474.3 (M+). HRMS (ESI(+)): Calcd. for C.sub.15H.sub.13B.sub.2O.sub.6 (diboronic acid) (M+H): 311.0898. Found: 311.0897.

EXAMPLE 9

(66) Pinacolyl Boronate Ester Prodrug of Resveratrol (FIG. 15)

(67) Step 1: A solution of trifluoromethanesulfonic anhydride (d 1.487, 3.7 mL, 19.5 mmol) in CH.sub.2Cl.sub.2 (5.0 mL) was added dropwise to a solution of pyridine (d, 0.9819, 1.96 mL, 24.3 mmol) and the corresponding phenol (1.2 g, 5.3 mmol) in anhydrous CH.sub.2Cl.sub.2 (10 mL) at 0 C. After complete addition, the mixture was warmed to room temperature and allowed to stir overnight. The mixture was then diluted with ethyl acetate, quenched with brine. The organic layer was separated. The aqueous solution was extracted with ethyl acetate. The combined organic solution was dried over MgSO.sub.4. After drying, the solvent was removed under reduced pressure and the residue was purified by flash column chromatography to give the triflates (3.3 g) quantatively. .sup.1H-NMR (CDCl.sub.3, 300 MHz): 7.63 (d, J=8.7 Hz, 2H), 7.46 (d, J=1.5 Hz, 2H), 7.33 (d, J=8.4 Hz, 2H), 7.21-7.04 (m, 3H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 149.8, 149.6, 141.3, 136.0, 131.6, 128.7, 126.7, 122.0, 119.3, 118.8 (q, J=319 Hz), 118.7 (q, J=319 Hz), 114.1.

(68) Step 2: The resveratrol triflates (1.24 g, 2 mmol), bis(pinacolato)diboron (1.66 g, 6.6 mmol), PdCl.sub.2(dppf) (0.14 g, 2.5 mol %) and KOAc (0.88 g, 9 mmol) in dioxane (5 mL) were stirred at 120 C. under nitrogen for 2 h. TLC and MS showed that the triflate was consumed completely and there is product to form. The solvent was removed under vacuum and the crude purified by flash chromatography to afford product (0.86 g). .sup.1H-NMR (CDCl.sub.3, 300 MHz): 8.19 (s, 1H), 8.07 (s, 2H), 7.81 (d, J=8.1 Hz, 2H), 7.52 (d, J=7.8 Hz, 2H), 7.23 (s, 2H), 1.37 (s, 12), 1.28 (s, 24H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 140.6, 140.2, 135.8, 135.1, 129.5, 128.6, 125.7, 83.9, 83.5, 25.0, 24.9. HRMS (ESI(+)): Calcd. for C.sub.14H.sub.18B.sub.3O.sub.6 (triboronic acid) (M+H): 313.1226. Found: 313.1228.

EXAMPLE 10

(69) Pinacolyl Boronate Ester Prodrug of Equol (FIG. 16)

(70) Step 1: Equol (1.22 g, 0.005 mol) was dissolved in DCM (30 mL), then trifluoromethanesulfonic acid anhydride (1.6 g, 0.0055 mol, d 1.677, 0.93 mL) and 4-dimethylaminopyridine (0.61 g, 0.005 mol) were added and the resulting mixture was stirred until the reaction was finished. The reaction was quenched with satd. sodium carbonate solution and extracted with ethyl acetate. The combined organic layer was dried over MgSO.sub.4 and concentrated. The crude was purified by flash column to afford solid product (1.71 g). .sup.1H-NMR (CDCl.sub.3, 300 MHz): 7.35-7.22 (m, 4H), 7.15 (d, J=9.0 Hz, 1H), 6.83-6.81 (m, 2H), 4.33 (m, 1H), 4.06 (m, 1H), 3.29 (m, 1H), 3.06-3.03 (m, 2H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 155.0, 148.7, 148.5, 141.1, 130.8, 129.2, 121.9, 121.8, 118.7 (q, J=318 Hz), 113.4, 109.9, 70.4, 37.5, 31.8. GC-MS: 506.1 (M+).

(71) Step 2: The triflate (0.51 g, 1.0 mmol), bis(pinacolato)diboron (0.63 g, 2.5 mmol), PdCl.sub.2(dppf) (0.014 g, 0.16 mmol) and potassium acetate (0.24 g, 2.4 mmol) was dissolved in dioxane (3 mL), then the mixture was stirred at 80 C. under microwave irradiation. The solvent was removed under vacuum and the crude purified by flash chromatography to afford product (0.10 g). .sup.1H-NMR (CDCl.sub.3, 300 MHz): 7.80 (d, J=7.8 Hz, 2H), 7.31-7.27 (m, 4H), 7.10 (d, J=7.5 Hz, 1H), 6.83-6.81 (m, 2H), 4.33 (m, 1H), 4.02 (t, J=10.2 Hz, 1H), 3.25 (m, 1H), 3.08-3.03 (m, 2H), 1.34 (s, 24H). .sup.13C-NMR (CDCl.sub.3, 75 MHz): 154.0, 144.6, 135.3, 129.3, 126.8, 126.5, 125.2, 122.8, 83.8, 83.7, 70.7, 38.8, 32.5, 24.8. GC-MS: 462.4 (M+). HRMS (ESI(+)): Calcd. for C.sub.15H.sub.17B.sub.2O.sub.5 (diboronic acid) (M+H): 299.1262. Found: 299.1268.

(72) All references cited in this specification are herein incorporated by reference as though each reference was specifically and individually indicated to be incorporated by reference. The citation of any reference is for its disclosure prior to the filing date and should not be construed as an admission that the present disclosure is not entitled to antedate such reference by virtue of prior invention.

(73) It will be understood that each of the elements described above, or two or more together may also find a useful application in other types of methods differing from the type described above. Without further analysis, the foregoing will so fully reveal the gist of the present disclosure that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this disclosure set forth in the appended claims. The foregoing embodiments are presented by way of example only; the scope of the present disclosure is to be limited only by the following claims.