A compound of the formula: ##STR1## wherein R.sup.1 is lower alkyl, R.sup.2 is hydrogen, lower alkyl or a heterocyclic group, R.sup.3 is hydrogen, lower alkyl or halogen, R.sup.4 is lower alkyl or halogen, R.sup.5 is nitro or amino substituted with substituent(s) selected from the group consisting of lower alkyl and acyl, and A is lower alkylene.
                            一种化合物的公式:##STR1## 其中R.sup.1是较低的烷基,R.sup.2是氢,较低的烷基或杂环基,R.sup.3是氢,较低的烷基或卤素,R.sup.4是较低的烷基或卤素,R.sup.5是硝基或
氨基,其上取代基选自较低的烷基和酰基,A是较低的烷基。