Pyrimidinyl cephalosporanic acid derivatives and pharmaceutical compositions

A compound of the formula:

• ##STR15## wherein R.sup.1 is a group of the formula:
• ##STR16## in which R.sub.a.sup.1 is hydrogen, amino or a protected amino group, R.sub.b.sup.1 and R.sub.c.sup.1 are each hydrogen, halogen, lower alkoxy, phenylthio, tolylthio, xylylthio, mesitylthio or naphthylthio,
• R.sup.2 is hydrogen or lower alkoxy,
• R.sup.3 is hydrogen or lower alkyl,
• R.sup.4 is hydrogen, halogen, carbamoyloxymethyl, lower alkyl, lower alkoxy, lower alkanoyloxymethyl or lower alkanoylthiomethyl,
• R.sup.5 is carboxy or a protected carboxy group, and
• X is a group of the formula:
• ##STR17## in which R.sup.6 is hydrogen, lower alkyl, mono to trihalo (lower) alkyl, lower alkenyl, lower alkynyl, phenyl, tolyl, xylyl, cumenyl, naphthyl, phenyl (lower) alkyl, mono or dihalo (lower) alkanoyl, or lower alkoxy, and non-toxic, pharmaceutically acceptable salts thereof.