abstract |
Compound of the general formula (1) wherein R 1 is a lower alkyl group, R 2 is hydrogen or isopropyl, R 3 is hydrogen, lower alkyl or -C (CH 3 ) HO-COOR 4 , wherein R 4 is lower alkyl or cyclohexyl, the moiety in the 4- or 8-position, and A is the grouping represents, and the salts thereof. |