| 摘要 |
<p>Optically active trans-6-substituted-5(R)-2-penem-3-carboxylic acid derivatives of formula <IMAGE> wherein R and R1 are each organic groups and R2 is hydrogen, a cation or a carboxy protecting group, are prepared by a multi-stage process of which the final steps involve reacting a 4(R) mercapto salt of formula <IMAGE> wherein M<n+> is a heavy metal cation of valency n and PHI is an aromatic, heterocyclic or alkyl radical, with a reactive derivative of an acid or thioacid of formula <IMAGE> wherein psi is oxygen or sulphur, and cyclizing the product.</p> |
