This invention concerns compounds of the formula: ##STR1## and the N-oxides and the pharmaceutically acceptable salts thereof wherein R.sub.1 is phenyl unsubstituted or substituted by fluoro chloro, bromo, alkyl of 1 to 3 carbon atoms or alkoxy of 1 to 3 carbon atoms; R.sub.2 is hydrogen or alkyl of 1 to 4 carbon atoms; R.sub.3 is hydrogen, nitro, amino, ##STR2## in which R.sub.4 is alkyl of 1 to 4 carbon atoms unsubstituted or substituted with up to three chlorine atoms or with three fluorine atoms on the same carbon atoms; R.sub.5 is alkyl of 1 to 4 carbon atoms n has a value of 0, 1 or 2.
                            本发明涉及以下式的化合物:##STR1##以及其N-氧化物和药学上可接受的盐,其中R.sub.1是苯基,未取代或取代为
氟、
氯、
溴、1至3个碳原子的烷基或1至3个碳原子的烷氧基;R.sub.2是氢或1至4个碳原子的烷基;R.sub.3是氢、硝基、
氨基、##STR2##其中R.sub.4是1至4个碳原子的烷基,未取代或取代有最多三个
氯原子或三个
氟原子,均在同一碳原子上;R.sub.5是1至4个碳原子的烷基,n的值为0、1或2。