Toluene → (S)-1-[[(S)-3-[[(Phenylmethoxy)carbonyl]amino]-2-oxo-1-azetidinyl]carbonyl]-2-azetidinecarboxylic acid, phenylmethyl ester

Participants

Reaction Steps

A slurry of (S)-3-[[(phenylmethoxy)carbonyl]amino]-2-azetidinone (0.44 g, 2 mmole) in 10 ml of dichloromethane was chilled to -10° C. under argon and treated with 0.3 g (3 mmoles) of triethylamine, followed by 3 ml (3.75 mmoles) of 12.5% phosgene in toluene. After 2 hours at -10° C., the mixture was evaporated in vacuo at 10° C., the residue taken up in 15 ml of dichloromethane at -10° C., and 0.4 g (4 mmole) of triethylamine was added followed by 0.45 g (2 mmole) of L-azetidine-2-carboxylic acid, phenylmethyl ester. After 30 minutes at 0° C., the reaction was extracted with 10% monobasic potassium phosphate and water, dried (sodium sulfate) and chromatographed on silica (LPS-1) (hexane:ethyl acetate, 1:1), to give the title compound (Rf=0.71 in ethyl acetate), 0.34 g.

Provenance & Evidence