Sodium hydride → (2S)-1-((tert-butoxy)carbonyl)-4-methylidenepyrrolidine-2-carboxylic acid

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Reaction Conditions

Reaction Steps

To a solution of methylenetriphenyl phosphorane, previously prepared from 37 g (777 mmol, 50% NaH in mineral oil, 4 eq) and 277.6 g (777 mmol, 4 eq) methyltriphenyl-phosphonium bromide in 1.5 l THF by stirring at 50° C. for 4 h, were added 44.5 g (194 mmol, leq) (2S)-4-Oxo-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester in 300 ml over a period of 30 min at RT. The suspension was stirred at 50° C. over night. After cooling to RT the suspension was added to a 5% NaHCO3 solution, washed with ether, the inorganic phase was acidified and extracted with EtOAc, washed with brine, dried over Na2SO4 and evaporated. 32.1 g (72%) (2S)-4-Methylene-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester were isolated as white solid.

Provenance & Evidence