4-Nitrobenzyl chloroformate → HCID 56637969, compound

Participants

Reaction Steps

To a solution of a mixture (5:1) of methyl 2-[(3S,4R)-3-{(1RS)-1-hydroxyethyl}-4-methylthio-2-oxoazetidin-1-yl]-3-methylbut-2-enoate (755 mg) and 4-dimethylaminopyridine (440 mg) in dichloromethane (6 ml) was added dropwise a solution of p-nitrobenzyl chloroformate (660 mg) in dichloromethane (4 ml) during three minutes period at 0° C. After 1.5 hours, the solution was concentrated, taken up into ethyl acetate (40 ml), and washed with dilute hydrochloric acid, water and brine. The organic layer was dried over magnesium sulfate and evaporated to leave an oil. Chromatography on silica gel (50 g) eluting with 2-10% ethyl acetate in dichloromethane to give methyl 3-methyl-2-[(3S,4R)-4-methylthio-3-{(1R)-1-(p-nitrobenzyloxycarbonyloxy)ethyl}-2-oxoazetidin-1-yl]but-2-enoate (974 mg).

Provenance & Evidence