Disclosed are a compound of the formula ##STR1## wherein R.sub.1 is lower alkyl, A is a group of the formula ##STR2## (in which R.sub.3 is hydrogen or lower alkyl) or methylene, and R.sub.2 is hydrogen or a group of the formula --(CH.sub.2).sub.n COOH (in which n is an integer of 1 to 6) or a salt of the derivative, and preparation thereof. The compounds have an excellent aldose reductase inhibitory action.
本发明涉及一种化合物,其
化学式为##STR1##其中,R.sub.1是低碳基,A是式##STR2##(其中R.sub.3是氢或低碳基)或亚甲基,R.sub.2是氢或式--(CH.sub.2).sub.n COOH(其中n是1至6的整数)的基团或其衍
生物的盐,并制备方法。该化合物具有优异的醛糖还原酶抑制作用。