Patent ID: 7538212

Claim:
A process for producing a β-lactam compound comprising protecting the hydroxyl group of a compound represented by formula (1): (wherein R 2 represents an aryl group or a heteroaryl group; and R 3 represents an alkyl group having 1 to 10 carbon atoms or a cycloalkyl group having 3 to 10 carbon atoms), to produce a compound represented by formula (2): (wherein R 1 represents a trimethylsilyl group or a triethylsilyl group; and R 2 and R 3 are the same as above); cyclizing the compound (2) in the presence of a strong base wherein the strong base is a base selected from the group consisting of an alkali metal alkoxide, an alkali metal amide, and an alkali metal hydride; and subsequently allowing the cyclized compound to react with diphenylphosphoryl chloride to produce a compound represented by formula (3) (wherein R 1 and R 3 are the same as above).