Acetic Acid → 1-Methoxycarbonyl-2-isopropylidene hydrazine

Hydrazinecarboxylic acid methyl ester (5.01 g) were dissolved in acetone (28 mL), and acetic acid (0.0636 mL) was added. The reaction mixture was stirred at room temperature for 24 hours. Water (50 mL) was added, and mixture was extracted three times with DCM (50 mL) and evaporated under vacuum, giving N′-Isopropylidene-hydrazine-carboxylic acid methyl ester (6.45 g, 89%). N′-Isopropyl-hydrazine-carboxylic acid methyl ester: N′-Isopropylidene-hydrazine-carboxylic acid methyl ester (6.45 g) were dissolved in ethanol (50 mL) and acetic acid (50 mL). PtO2 (0.231 g) was added, and reaction was stirred at room temperature for 22 hours under an atmosphere of hydrogen. Mixture was evaporated under vacuum, giving N′-Isopropyl-hydrazine-carboxylic acid methyl ester (5.08 g, 77%) as a white solid. N′-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-N′-isopropyl-hydrazine-carboxylic acid methyl ester: Triphosgene (1.05 g) was dissolved in DCM (17 mL) and stirred at 0° C. N′-Isopropyl-hydrazine-carboxylic acid methyl ester (1.00 g) and DIPEA (1.5 mL) were dissolved in DCM (25 mL), and mixture was added to triphosgene solution and stirred for 10 minutes. 5-(4-Bromo-phenyl)-2-pyrrolidin-2-yl-1H-imidazole (2.65 g) was added. Reaction was stirred at room temperature for 1 hour and extracted twice with water (10 mL), once with brine (10 mL), and evaporated under vacuum. The resulting oil was subjected to silica gel chromatography using a 40 g ISCO column and effluent of 0-100% ethyl acetate:hexanes. The fractions containing product were combined and the solvent was removed under vacuum, giving N′-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-N′-isopropyl-hydrazine-carboxylic acid methyl ester (533 mg, 16%). N′-Isopropyl-N′-(2-{5-[4-(4,4,5,5-tetramethyl[1,3,2]dioxaborolan-2-yl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-hydrazinecarboxylic acid methyl ester: N′-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-N′-isopropyl-hydrazine-carboxylic acid methyl ester (0.533 g), 4,4,5,5,4′,4′,5′,5′-Octamethyl-[2,2]-bi[[1,3,2]dioxaborolanyl] (0.644 g), and KOAc (0.309 g) were dissolved in dioxane (8 mL). The solution was degassed with nitrogen, and Pd(PPh3)4 (0.0562 g) was added, and reaction was stirred at 80° C. for 2 days. Solid was removed by vacuum filtration, and solvent was removed under vacuum. The resulting oil was subjected to silica gel chromatography using a 40 g ISCO column and effluent of 0-5% MeOH:DCM. The fractions containing product were combined and the solvent was removed under vacuum, giving N′-Isopropyl-N′-(2-{5-[4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-hydrazinecarboxylic acid methyl ester (0.564 g, 96%) as a yellow solid. N′-Isopropyl-N′-{2-[5-(4′-{2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-biphenyl-4-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-hydrazinecarboxylic acid methyl ester: N′-Isopropyl-N′-(2-{5-[4-(4,4,5,5-tetramethyl-[1,3 ,2]dioxaborolan-2-yl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-hydrazinecarboxylic acid methyl ester (0.295 g), (1-{2-[5-(6-Bromophenyl-2-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-2-methyl-propyl)-carbamic acid methyl ester (0.280 g), and NaHCO3 were dissolved in DME (9 mL) and water (3 mL). The solution was degassed with nitrogen, and Pd(PPh3)4 (0.0282 g) was added, and reaction was stirred at 85° C. for 19 hours. Solvent was removed under vacuum. Solid was dissolved in DMF, purified by reverse phase HPLC (5-70% acetonitrile:water) two times, and lyophilized, giving N′-Isopropyl-N′-{2-[5-(4′-{2-[1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-biphenyl-4-yl)-1H-imidazol-2-yl]-pyrrolidine-1-carbonyl}-hydrazinecarboxylic acid methyl ester (0.017 g, 4%) as a white solid.

1. extractionmixture was extracted three times with DCM (50 mL)
2. customevaporated under vacuum

ORD record

ord-7ea16716a61e42dd993cee0234fd6033

Source dataset

uspto-grants-2012_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08273341B2