| 摘要 |
Novel pharmaceutically useful compounds of the formula <IMAGE> wherein Y is FCH2-, F2CH- or F3C-; R is hydrogen, (C1-4alkyl)carbonyl, (C1-4alkoxy) carbonyl or -CO-CHR3-NH2 wherein R3 is hydrogen, C1-4alkyl, benzyl or p- hydroxybenzyl; either R1 and R2 are the same or different and are each hydrogen of C1-4alkyl or R1 is hydrogen and R2 is fluorine; and pharmaceutically acceptable salts and individual optical isomers thereof. |
