Dimethyl Sulfoxide → Carbamic acid, (2-oxocyclopentyl)-, 1,1-dimethylethyl ester, (S)- (9CI)

Participants

Reaction Conditions

Reaction Steps

A mixture of oxalyl chloride (6.47 mL, 74.5 mmol) in THF (166 mL) is cooled to −72° C. under nitrogen and treated dropwise with DMSO (10.59 mL, 149.1 mmol). The mixture is stirred for 5 min, whereupon tert-butyl (1S,2S)-2-hydroxycyclopentylcarbamate (10.0 g, 49.7 mmol) is added. Stirring is continued at −75° C. for 45 min. Triethylamine (37.4 mL, 268.3 mmol) is added slowly keeping the temperature below −68° C. After the addition is complete the reaction is allowed to warm slowly to room temperature overnight. The reaction is combined with the reaction mixture from a pilot reaction (200 mg scale) completed earlier. Water (100 mL) is added and the reaction is concentrated in vacuo to remove THF. The mixture is extracted with EtOAc (3×150 mL). The combined organic portions are dried over sodium sulfate, filtered, and concentrated to give 12.41 g of crude product as a yellow oil. The material is purified on silica gel (330 g, 10-40% EtOAc/hexanes) to give the title compound (9.17 g, 93%). 1H-NMR (400 MHz, CDCl3) δ 5.04-5.02 (m, 1H), 3.98-3.96 (m, 1H), 2.65-2.63 (m, 1H), 2.44-2.39 (m, 1H), 2.21-2.11 (m, 1H), 2.04 (s, 1H), 1.89-1.85 (m, 1H), 1.66-1.59 (m, 1H), 1.44 (s, 9H). GC-MS m/z 199 (M+). [a]D20=+96.9° (c 1.0, CHCl3) [literature (Aube, J.; Wolfe, M. S.; Yantiss, R. K.; Cook, S. M.; Takusagawa, F. Synthetic Communications 1992, 22, 3003-3012) [a]D25=+125° (c 0.2, CHCl3)].

Provenance & Evidence