Ammonium Chloride → 1-tert-butyl 2-methyl (2S)-4-methylidenepyrrolidine-1,2-dicarboxylate

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Reaction Conditions

Reaction Steps

Methyltriphenylphosphonium bromide (22 g, 61.6 mmol) was added to a solution of potassium tert-butoxide (6.5 g, 57.6 mmol) in anhydrous diethyl ether (450 ml) at 0° C. under nitrogen and the resulting bright yellow mixture stirred for 30 minutes. A solution of 1-tert-butyl 2-methyl (2S)-4-oxo-1,2-pyrrolidinedicarboxylate (10 g, 41.1 mmol in 150 ml anhydrous diethyl ether) was added slowly to the reaction mixture, which was then warmed at 35° C. for 3 h. Saturated aqueous ammonium chloride solution (0.5 ml) was then added. The organic layer was removed, and the aqueous washed with diethyl ether (3×5 ml). The combined organic layers were dried with brine and magnesium sulfate before filtering and removal of solvent. Silica gel chromatography, eluting with 15% ethyl acetate in hexanes gave the desired product 6.9 g (70% yield) as a off-white wax.

Provenance & Evidence