| 摘要 |
<p><IMAGE> Azetidinones of the above formula (R1=H or a group which can be replaced by H in a single step reaction proceeding under mild conditions, R2=H or a hydroxy protecting group, R3= substituted or unsubstituted alkyl or aryl, R4=H, lower alkyl, phenyl, or substituted phenyl) are useful intermediates in the preparation of penems. Their preparation is also described.</p> |
