Compounds of the formula: ##STR1## in which R.sub.1 represents a hydrogen atom or a (C.sub.1 -C.sub.4)alkyl group, R.sub.2 represents a hydrogen atom, a (C.sub.1 -C.sub.4)alkoxycarbonyl group, a carboxyl group, a sodium carboxylate group, a group --CH.sub.2 OR.sub.4, where R.sub.4 is a hydrogen atom or R.sub.4 is a (C.sub.1 -C.sub.4) alkyl or (C.sub.1 -C.sub.4) acyl group, a group --CONR.sub.5 R.sub.6, or a group --CN.sub.4 R.sub.5, where R.sub.5 is a hydrogen atom or a (C.sub.1 -C.sub.4)alkyl group and R.sub.6 is a hydrogen atom or a (C.sub.1 -C.sub.4)alkyl, hydroxyl or (C.sub.1 -C.sub.4) alkoxy or (C.sub.1 -C.sub.3) alkoxyphenyl group and R.sub.3 represents a (C.sub.1 -C.sub.4)alkyl group, and their acid addition salts are useful as synthetic intermediates.
化学式为:##STR1## 其中R.sub.1代表氢原子或(C.sub.1-C.sub.4)烷基,R.sub.2代表氢原子、(C.sub.1-C.sub.4)烷氧羰基、羧基、
钠羧酸盐基、--CH.sub.2 OR.sub.4基团,其中R.sub.4为氢原子或(C.sub.1-C.sub.4)烷基或(C.sub.1-C.sub.4)酰基基团、--CONR.sub.5 R.sub.6基团,或--CN.sub.4 R.sub.5基团,其中R.sub.5为氢原子或(C.sub.1-C.sub.4)烷基,R.sub.6为氢原子或(C.sub.1-C.sub.4)烷基、羟基或(C.sub.1-C.sub.4)烷氧基或(C.sub.1-C.sub.3)烷氧基苯基基团,R.sub.3代表(C.sub.1-C.sub.4)烷基,它们的酸加合物盐在合成中间体中有用。