| 摘要 |
1. A cephalosporin derivatives of the general formula <IMAGE> (I) wherein R1 is an alpha -, beta - or gamma -amino acid residue (bonded by the ester linkage), which may optionally be substituted by one or two lower alkyl groups at the amino group thereof, R2 is an 1-alkanoyloxyalkyl, 1-alkoxycarbonyloxyalkyl, phthalidyl or 5-methyl-1,3-dioxolen-2-on-4-ylmethyl group, R3 is a carbamoyloxymethyl group, which may optionally be substituted by one or two lower alkyl groups, or a heterocyclothiomethyl group, which may optionally be substituted by one or more appropriate substituents, and R4 is a hydrogen atom or a hydroxy group, or its non-toxic salt are found to be useful as orally administrable antibiotics having broad antimicrobial activities against both gram-positive and gram-negative bacteria. |
