A member selected from the group consisting of a compound of the formula ##STR22## wherein X is a member selected from carboxy and C.sub.1 - C.sub.6 alkoxy-containing carbalkoxy, and each of R.sub.1, R.sub.2 and R.sub.3 is a member selected from the group consisting of (1) hydrogen, (2) C.sub.1 - C.sub.10 alkyl, (3) C.sub.2 - C.sub.6 alkyl-containing alkenyl, (4) C.sub.6 - C.sub.10 aryl which is unsubstituted or substituted by a member of a group consisting of C.sub.1 - C.sub.5 alkyl, halogen, nitro, C.sub.1 - C.sub.5 alkylamino, hydroxy and C.sub.1 - C.sub.5 alkoxy, (5) C.sub.1 - C.sub.4 alkyl-containing alkylamino, (6) C.sub.1 - C.sub.6 alkyl-containing alkylmercapto, (7) nitro, (8) cyano, (9) C.sub.1 - C.sub.2 alkyl-containing alkylsulfonyl, (10) carboxy, (11) C.sub.1 - C.sub.6 alkoxy-containing carbalkoxy, (12) C.sub.1 - C.sub.6 alkyl-containing hydroxyalkyl, (13) C.sub.1 - C.sub.3 alkyl-containing aminoalkyl, (14) C.sub.1 - C.sub.2 hydroxyalkylamino, and (15) C.sub.1 - C.sub.2 alkyl-containing acetoxyalkylamino and a pharmaceutically acceptable acid addition salt thereof.