Benzyl 6-oxa-3-azabicyclo(3.1.0)hexane-3-carboxylate → benzyl (3S,4R)-3-hydroxy-4-methylpyrrolidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

To solution of benzyl 6-oxa-3-azabicyclo[3.1.0]hexane-3-carboxylate (9.6 g, 43.8 mmol) in THF (150 mL) was added copper cyanide (3.92 g, 43.8 mmol) and the resulting suspension was cooled to −20° C. with dry ice-ice-water-acetone bath. Methylmagnesium bromide (3 M in diethylether) (29.2 mL, 88 mmol) was added via syringe dropwise and the resulting mixture was stirred at this temperature for 1 h. At this time, TLC analysis of the resulting slurry (after quenching an aliquot with MeOH) indicated total comsumption of substrate to give a single, more polar component. At this time, the reaction was carefully quenched at −20° C. by a slow dropwise addition of 50 mL of sat. aq. ammonium chloride. The cooling bath was removed and the mixture was allowed to stir vigorously for 1 h while warming to rt. Solid was removed by vacuum filtration through Celite and the filter cake was rinsed with dichloromethane (80 mL×3). The resulting two layers of the filtrate were separated and the aqueous portion was extracted with dichloromethane (80 mL). The combined organic portions were washed with brine and dried over magnesium sulfate, filtered and concentrated to afford the title compound as a clear oil (9.2 g, 39.1 mmol, 89% yield). HPLC (method B) retention time=2.64 min. and LCMS (m+1)=236.2.

Provenance & Evidence