4-Nitrobenzyl chloroformate → HCID 56629932, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of a mixture (1:3) of methyl 2-[(3S,4R)-3-{(1RS)-1-hydroxyethyl}-4-methylthio-2-oxoazetidin-1-yl]-3-methylbut-2-enoate (1.84 g) and 4-dimethylaminopyridine (1.23 g) in dichloromethane (20 ml) was added a solution of p-nitrobenzyl chloroformate (1.60 g) in dichloromethane (3 ml) at 0° C. After stirring at 0° C. for 1.5 hours, the mixture was diluted with ethyl acetate (150 ml) and washed with dilute hydrochloric acid, water, a dilute aqueous sodium bicarbonate, and brine. Drying over magnesium sulfate and removal of the solvent left an oil (3.1 g), which was chromatographed on silica gel (90 g) eluting with 10-25% ethyl acetate in hexane to give a mixture (1:3) of methyl 3-methyl-2-[(3S,4R)-4-methylthio-3-{(1RS)-1-(p-nitrobenzyloxycarbonyloxy)ethyl}-2-oxoazetidin-1-yl]-but-2-enoate (2.90 g) as an oil.

Provenance & Evidence