| abstract |
Compounds of the formula <IMAGE> I wherein R1 is hydrogen or a conventional amino-protecting group, R2 and R3 each are independently methyl or ethyl, and R4 is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, allyl, 2-butenyl, 3-butenyl, 2-hydoxyethyl, 3-hydroxypropyl, 2-(dimethylamino)ethyl, pyridylmethyl, pyridylethyl, benzyl or phenethyl, and nontoxic pharmaceutically acceptable acid addition salts and solvates thereof, as well as processes for their preparation, are disclosed. The compounds in which R1 is hydrogen are potent antibacterial agents. |