| 摘要 |
<p>A process is provided for preparing (trans)-4-phenyl-DL-proline derivatives, which are useful in preparing certain angiotensin converting enzyme inhibitors, which process involves reacting an ester of the structure <CHEM> wherein X is a leaving group such as tosylate, R<3> is lower alkyl, R is cyclohexyl, phenyl or substituted phenyl, and R<1a> is a protecting group, with a potassium amide base such as potassium hexamethyldisilazide under reduced temperatures to form the trans-4-substituted proline ester derivative of the structure <CHEM> then hydrolyzing the proline ester to the acid of the structure <CHEM> and removing the R<1a> nitrogen protecting group to form the unprotected acid of the structure <CHEM> a</p> |
