| 摘要 |
A process for preparing a 4-acyloxyazetidinone or a derivative thereof represented by formula (IV): (* CHEMICAL STRUCTURE *) (IV) wherein R1 represents a hydrogen atom, a lower alkyl group, a hydroxyethyl group, or a protected hydroxyethyl group; R3 represents an alkyl group having from 1 to 10 carbon atoms which may be substituted with a halogen atom, a cyano group, a lower alkoxy group or a phenyl group, or a substituted or unsubstituted phenyl group, provided that the (alpha)-positioned carbon atom of said alkyl group should not have more than two halogen atoms; and R4 represents a hydrogen atom, a lower alkyl group, or a lower alkoxycarbonyl group, which is useful as an intermediate for penem antibiotics is disclosed, comprising reacting azetidinone or a derivative thereof represented by formula (II): (* CHEMICAL STRUCTURE *) (II) wherein R1 is as defined above, and R2 represents a hydrogen atom, a lower alkyl group, a lower alkoxycarbonyl group, or a carboxyl group, with a carboxylic acid represented by formula (III): R3COOH (III) wherein R3 is as defined above, in the presence of (1) a transition metal compound selected from a ruthenium compound, an osmium compound, and a cobalt compound, (2) an aldehyde having 2 or more carbon atoms, provided that the carbon atom at the (alpha)-position thereof should not have two or more halogen atoms, and (3) oxygen. The compound (IV) can be prepared with safety through simple and easy operations.
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