Imidazole → (2S,4R)-4-(tert-Butyl-diphenyl-silanyloxy)-1-(4-trifluoromethoxy-phenylcarbamoyl)-pyrrolidine-2-carboxylic acid methyl ester

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Reaction Steps

TBDPSCl (1.73 g, 6.3 mmol) was dropped into a solution of (2S,4R)-4-Hydroxy-1-(4-trifluoromethoxy-phenylcarbamoyl)-pyrrolidine-2-carboxylic acid methyl ester (1.0 g, 2.9 mmol) and imidazole (0.98 g, 14.4 mmol) in DMF (20 mL), the mixture was stirred at room temperature for 4 hours. Then the mixture was poured into water (50 mL), extracted with ethyl acetate (3×30 mL). The organic layers was combined, washed with water (2×30 mL), brine (30 mL), then dried over anhydrous sodium sulfate, filtered and concentrated. The residue was purified by silica gel column chromatography (ethyl acetate/petroleum ether=1:5) to give compound 1.48 g (88%) of the title compound. 1H NMR (300 MHz, CDCl3): δ 7.67-7.62 (m, 4H), 7.47-7.37 (m, 8H), 7.13 (d, 2H, J=8.7 Hz), 6.37 (s, 1H), 4.68-4.55 (m, 2H), 3.71 (s, 3H), 3.54-3.42 (m, 2H), 2.33-2.25 (m, 1H), 2.05-1.97 (m, 1H), 1.06 (s, 9H); LC-MS: 587.2 [M+1]+.

Provenance & Evidence