| abstract |
A compound of formula ** (See formula) ** wherein R1 is C1-7 alkyl or C1-7 alkoxy-C1-7 alkyl; R2 is selected from the group consisting of hydrogen, halogen, C1-7 alkoxycarbonyl-C1-7 alkyl and C1-7 alkoxycarbonyl-C2-7 alkenyl; R3 is hydrogen; R4 is selected from the group consisting of -O- (CH2) m-NHR5 and -O- (CO) - (CH2) n-NHR6, where m is 2, n is 1, R5 is hydrogen, and R6 is hydrogen ; or pharmaceutically acceptable salts thereof. |