Compounds having the structure ##STR1## and the pharmaceutically acceptable salts thereof, wherein R.sub.1 is hydrogen, halogen, hydroxy, alkanoyloxy, alkoxy, alkylthio, alkyl or trifluoromethyl; R.sub.2 is hydrogen, alkyl or alkenyl; R.sub.3 is hydrogen, halogen or alkyl; R.sub.4 is formyloxy or alkanoyloxy; m is 1 or 2; and n is 0, 1 or 2; have useful physiological activity.
具有结构##STR1##及其药学上可接受的盐,其中R.sub.1是氢、卤素、羟基、烷酰氧基、烷氧基、烷基
硫基、烷基或三
氟甲基;R.sub.2是氢、烷基或烯基;R.sub.3是氢、卤素或烷基;R.sub.4是甲酰氧基或烷酰氧基;m为1或2;n为0、1或2;具有有用的生理活性。