2,2-Difluoro-2-(fluorosulfonyl)acetic acid → 4-Difluoromethoxy-pyrrolidine-1,2-dicarboxylic acid 2-[2-(4-bromo-phenyl)-2-oxo-ethyl]ester 1-tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To 4-Hydroxy-pyrrolidine-1,2-dicarboxylic acid 2-[2-(4-bromo-phenyl)-2-oxo-ethyl]ester 1-tert-butyl ester (500 mg) and Cu(I)I (45 mg) in MeCN (8 mL) at 45° C. was added 242 μl of difluoro-fluorosulfonyl-acetic acid in 2 mL of MeCN dropwise for 60 min. The reaction mixture was stirred at 45° C. for 60 min. and evaporated under reduced pressure, and resulting residue was taken up in ethyl acetate (100 mL). The organic phase was washed with brine (1×100 mL) and dried over sodium sulfate. After the solvent was removed, the resulting oil was subjected to silica gel chromatography using effluent of 10-50% ethyl acetate and hexanes. The fractions containing product were combined and the solvent was removed under reduced pressure to provide 4-Difluoromethoxy-pyrrolidine-1,2-dicarboxylic acid 2-[2-(4-bromo-phenyl)-2-oxo-ethyl]ester 1-tert-butyl ester (339 mg, 61%) as a clear oil. 2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl-4-difluoromethoxy-pyrrolidine-1-carboxylic acid tert-butyl ester: Title compound was prepared according to the method employed to prepare 2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl]-4-hydroxy-pyrrolidine-1-carboxylic acid tert-butyl ester (Example 1), substituting 4-Difluoromethoxy-pyrrolidine-1,2-dicarboxylic acid 2-[2-(4-bromo-phenyl)-2-oxo-ethyl]ester 1-tert-butyl ester (305 mg) for 4-Hydroxy-pyrrolidine-1,2-dicarboxylic acid 2-[2-(4-bromo-phenyl)-2-oxo-ethyl]ester 1-tert-butyl ester (244 mg, 83%). (1-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl-4-difluoromethoxy-pyrrolidine-1-carbonyl}-2-methoxy-propyl)-carbamic acid methyl ester: To 2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl-4-difluoromethoxy-pyrrolidine-1-carboxylic acid tert-butyl ester (244 mg) in DCM (4 mL) was added 4N HCl in dioxanes (1.3 mL). The mixture was stirred for 1 hours then concentrated to afford the HCl salt of the crude amine. To the crude amine in DMF (2.7 mL) was added N-methylmorpholine (234 μL). After all material dissolved, 2-methoxycarbonylamino-3-methyl-butyric acid (103 mg) and HATU (263 mg) were added. After stirring for 60 min. the reaction was evaporated under reduced pressure, and resulting residue was taken up in ethyl acetate (100 mL). The organic phase was washed with saturated sodium bicarbonate (1×100 mL) and dried over sodium sulfate. After the solvent was removed, the resulting oil was subjected to silica gel chromatography using effluent of 80-100% ethyl acetate and hexanes. The fractions containing product were combined and the solvent was removed under reduced pressure to provide (1-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl-4-difluoromethoxy-pyrrolidine-1-carbonyl}-2-methoxy-propyl)-carbamic acid methyl ester (166 mg, 61%) as a clear oil. 2-{5-[6-(4-{2-[4-Difluoromethoxy-1-(2-methoxycarbonylamino-3-methyl-butyryl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-phenyl)-naphthalen-2-yl]-1H-imidazol-2-yl}-pyrrolidine-1-carboxylic acid tert-bytyl ester: To (1-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl-4-difluoromethoxy-pyrrolidine-1-carbonyl}-2-methoxy-propyl)-carbamic acid methyl ester (166 mg) and 2-{5-[6-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-naphthalen-2-yl]-1H-imidazol-2-yl}-pyrrolidine-1-carboxylic acid tert-butyl ester (237 mg) in DME (1.6 mL) were added Pd2(dba)3 (15 mg), Xanphos (19 mg), and 2M K3PO4 (483 μl). After stirring for overnight at 80° C., the mixture was filtered and evaporated under reduced pressure, and resulting residue was subjected to silica gel chromatography using effluent of 10-15% MeOH and DCM. The fractions containing product were combined and the solvent was removed under reduced pressure to provide the title product (30 mg, 12%) as a clear film. [1-(4-Difluoromethoxy-2-{5-[4-(6-{2-[1-(2-methoxycarbonylamino-2-phenyl-acetyl)-pyrrolidin-2-yl]-3H-imidazol-4-yl}-naphthalen-2-yl)-phenyl]-1H-imidazol-2-yl}-pyrrolidine-1-carbonyl)-2-methyl-propyl]carbamic acid methyl ester: Title compound was prepared according to the method employed to prepare (1-{2-[5-(4-Bromo-phenyl)-1H-imidazol-2-yl-4-difluoromethoxy-pyrrolidine-1-carbonyl}-2-methoxy-propyl)-carbamic acid methyl ester (Example 5), substituting methoxycarbonylamino-phenyl-acetic acid (30 mg) for 2-methoxycarbonylamino-3-methyl-butyric acid (22 mg, 58%). 1H NMR (MeOH-d4, 400 MHz) δ: 8.20-8.05 (m, 3H), 7.95-7.72 (m, 5H), 7.56-7.35 (m. 8H), 7.15 (m, 1H), 6.71-6.35 (m, 1H), 5.55 (m, 1H), 5.30-5.20 (m, 3H), 5.05-4.90 (m, 3H), 4.36 (m, 1H), 4.20 (m, 1H), 4.12-3.82 (m, 2H), 3.65 (m, 6H), 3.50 (m, 1H), 2.75 (m, 1H), 2.45 (m, 1H), 2.35-1.90 (m, 2H), 0.98-0.85 (m, 6H); MS (ESI) m/z 889.3 [M+H]+.

Provenance & Evidence