An increase in the diastereoselectivity resulting from the reaction of a phosphinic acid ester of the formula
with the halo ester of the formula
is achieved by carrying out the reaction in the presence of 4-methylmorpholine, diazabicyclooctane, quinuclidine, 1-methylpyrolidine, or cinchonidine. After removal of the R3 protecting group and fractional crystallization, the resulting desired diastereomeric pair can be resolved, and the desired isomer can be coupled to 4-substituted L-proline to give compounds possessing angiotensin converting enzyme inhibition activity. In particular, the process is useful in producing the antihypertensive agent fosinopril sodium in increased yields.
式的
膦酸酯与式的卤代酯反应所产生的非对映选择性的提高
与式
通过在 4-甲基吗啉、二氮杂双
环辛烷、
奎尼丁、
1-甲基吡咯烷或
辛可尼丁存在下进行反应,可提高反应的非对映选择性。除去 R3 保护基团并进行分馏结晶后,可分离出所需的非对映异构体对,并将所需的异构体与 4-取代的
L-脯氨酸偶联,得到具有
血管紧张素转换酶抑制活性的化合物。特别是,该工艺有助于提高抗高血压药物
福辛普利钠的产量。