An optical isomer of a compound having the formula: ##STR1## wherein the two methyl groups at 4- and 6-positions of the dioxaphosphorinane ring assume trans configurations to each other, which has a levo-rotatory angle of optical rotation attributable to the asymmetric carbon atom at 4-position of the dihydropyridine ring, and a pharmaceutically acceptable salt thereof.
该化合物的光学异构体的分子式为:##STR1## 其中二氧杂
磷环的4-和6-位上的两个甲基基团相对构型为反式,该化合物具有左旋光旋转角度,归因于
二氢吡啶环4-位的不对称碳原子,并且其药学上可接受的盐。