Dicyclohexylcarbodiimide → (3S, 4R)-3-[(R)-1-t-Butyldimethylsilyloxyethyl]-4-([(S)-1-[N-(p-nitrobenzyloxycarbonyl)acetimidoyl]-pyrrolidin-3-ylthio]carbonylmethyl)-2-azetidinone

Participants

Reaction Steps

2.67 mg (0.93 mmole) of (3S, 4R)-3-[(R)-1-t-butyldimethylsilyloxyethyl]-4-carboxymethyl-2-azetidinone and 330 mg (1.02 mmole) of (S)-3-mercapto-1-[N-(p-nitrobenzyloxycarbonyl)acetimidoyl]pyrrolidine were dissolved in 5 ml of benzene. 210 mg (9.02 mmole) of dicyclohexylcarbodiimide and 5 mg (0.04 mmole) of 4-dimethylaminopyridine were added, and the mixture was stirred at room temperature for 1 hour, after which insolubles were filtered off. The filtrate was concentrated to dryness by evaporation under reduced pressure and the resulting oily residue was purified by column chromatography through 15 g of silica gel eluted with mixtures of benzene and ethyl acetate in volume ratios from 1:2 to 1:5, to give 495 mg (yield 90%) of the title product in the form of an oil.

Provenance & Evidence