Imidazole → (2S,4R)-1-tert-Butyl 2-methyl 4-((tert-butyldimethylsilyl)oxy)pyrrolidine-1,2-dicarboxylate

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Reaction Steps

Methyl (2S,4R)—N-tert-butoxycarbonyl-4-hydroxy-2-pyrrolidinecarboxylate (22.1 g, 82.6 mmol) was dissolved in dry DMF (100 mL) under nitrogen. Imidazole (16.8 g, 248 mmol) was added and the mixture cooled to 0° C. tert-Butyldimethylsilyl chloride (13.1 g, 86.7 mmol) was added in small portions and then the mixture was allowed to warm to room temperature. After stirring overnight, the mixture was diluted with 300 mL ethyl acetate and washed with water three times (500 mL, 200 mL, 200 mL). The organic extracts were washed one final time with brine and then dried over MgSO4, filtered and concentrated to give 29.5 g (99%) of desired product as a colorless oil. LC/MS (M-Boc+H)+ m/z=260.2. 1H NMR (CDCl3) δ 4.30-4.47 (m, 2H), 3.73 and 3.75 (s, 3H), 3.60 (m, 1H), 3.28-3.45 (m, 1H), 2.18 (m, 1H), 2.03 (m, 1H), 1.42 and 1.47 (s, 9H), 0.87 (s, 9H), 0.06 (s, 6H).

Provenance & Evidence