| 摘要 |
<p>A process for preparing a 4-acyloxyazetidinone or derivative thereof represented by: <CHEM> wherein R<1> represents hydrogen, C1-5 alkyl, hydroxyethyl or a protected hydroxyethyl group; R<3> represents C1-10 alkyl which may be substituted with halogen, cyano, C1-5 alkoxy or phenyl, or an optionally substituted phenyl group, provided that the alpha -positioned carbon atom of said alkyl group does not have more than 2 halogen atoms; and R<4> represents hydrogen, C1-5 alkyl, or C2-6 alkoxycarbonyl, comprises reacting azetidinone or a derivative thereof represented by: <CHEM> wherein R<1> is as defined above, and R<2> represents hydrogen, C1-5 alkyl, C2-6 alkoxycarbonyl, or carboxyl, with a carboxylic acid R<3>COOH where R<3> is as above, in the presence of (1) a Ru, Os or Co transition metal compound, (2) an aldehyde having 2 or more C atoms, provided that the alpha -C has not more than one halogen atom, and (3) oxygen gas. The compound (IV) is prepared with safety through simple and easy operations and is useful as an intermediate for making penem antibiotics. Of the products (IV) one is novel, wherein R<1> includes t-butyl-dimethyl-SiO and R<3>R<4> is-OCOCHaOb where a is 1 or 2 and b is 2 when a is 1 and is 1 when a is 2.</p> |
