| 摘要 |
A process is provided for preparing 4-hydroxy-4-phenyl-proline derivatives of the structure <IMAGE> wherein R1 is a nitrogen protecting group such as benzoyl, benzyloxycarbonyl, t-butoxycarbonyl, benzyl, benzhydryl, trityl, acetyl, trifluoromethylacetyl, sulfonamides, and the like and wherein X is OR2 and R2 is hydrogen or an acid protecting group such as lower alkyl, aryl-lower alkyl or a metal ion, such as Na or K, or X is NR3R4 wherein R3 and R4 may be the same or different and are hydrogen, lower alkyl, aryl or arylalkyl, or R3 and R4 together with the nitrogen to which they are attached form a 5-, 6- or 7-membered ring. The process includes the steps of forming triphenylcerium [(C6H5)3Ce], for example, by reacting cerium trichloride (CeCl3) with phenyllithium, and reacting the triphenylcerium with the keto acid <IMAGE> in the presence of an inert organic solvent such as tetrahydrofuran. The 4-hydroxy-4-phenyl-proline derivatives used in the preparation of 4-substituted proline derivatives which are employed for preparing certain angiotensin-converting enzyme inhibitors.
|
