A process for the preparation of a compound of formula (III) ##STR1## by hydrolyzing a compound of formula (I) or (II) ##STR2## wherein R.sup.1 and R.sup.2, which may be the same or different, are selected from C.sub.1-8 alkyl, C.sub.3-8 cycloalkyl, and optionally substituted aryl, in the presence of acid at a pH above 2.0.
一种制备式(III)化合物的方法 ##STR1## 通过在酸的存在下,在pH大于2.0的条件下
水解式(I)或(II)化合物 ##STR2## 其中R.sup.1和R.sup.2(可能相同或不同)选自C.sub.1-8烷基,C.sub.3-8环烷基和可选取代芳基。