| 摘要 |
<p>A process for producing a 4-substituted azetidinone derivative represented by general formula (I) wherein R represents hydrogen or a nitrogen-protecting group; R<1> represents an optionally protected hydroxyl group or an optionally halogenated alkyl group; R<2> represents hydrogen or alkyl; R<3> represents alkyl, optionally substituted phenyl, etc; and R<4> represents an electron-attractive group; or alternatively R<3> and R<4> are combined together to form a ring, by the reaction of an azetidinone derivative represented by general formula (II) wherein R and R<1> are as defined above, and Z represents a leaving group, with an imide compound represented by general formula (III) wherein R<2>, R<3> and R<4> are each as defined above, in the presence of a base and a titanium compound represented by general formula Ti(Cl)n(OR<5>)m wherein R<5> represents lower alkyl, 0 </= n </= 4,0 </= m </= 4 and n + m = 4. The obtained derivative can be readily converted into a carboxylic acid as an important intermediate for preparing carbopenem compounds. <CHEM></p> |
