Abstract: Novel cephalosporins which has attached to the exomethylene group at the 3-position of the cephem ring a substituted or unsubstituted aryl, acylamino, aromatic heterocyclic, triazolyl or tetrazolyl group, said aromatic heterocyclic group being attached through a carbon-carbon bond and said triazolyl or tetrazolyl group being attached through a carbon-nitrogen bond, and has the following group attached to the amino group at the 7-position: ##STR1## wherein A represents a group of the formula, --CH.sub.2 -- or a group of the formula ##STR2## in which R.sup.5 represents a hydrogen atom or an alkyl group, and the bond.about.represents syn or anti isomer or their mixture; R.sup.3 represents a hydrogen or halogen atom; and R.sup.4 represents a hydrogen atom or an amino group which may be protected or substituted. These cephalosporins have a broad antibacterial spectrum, are stable against .beta.-lactamase produced by bacteria, have a low toxicity, and are well absorbed when administered orally or parenterally.

Abstract: Novel cephalosporins which has attached to the exomethylene group at the 3-position of the cephem ring a substituted or unsubstituted aryl, acylamino, aromatic heterocyclic, triazolyl or tetrazolyl group, said aromatic heterocyclic group being attached through a carbon-carbon bond and said triazolyl or tetrazolyl group being attached through a carbon-nitrogen bond, and has the following group attached to the amino group at the 7-position: ##STR1## wherein A represents a group of the formula, --CH.sub.2 -- or a group of the formula ##STR2## in which R.sup.5 represents a hydrogen atom or an alkyl group, and the bond represents syn or anti isomer or their mixture; R.sup.3 represents a hydrogen or halogen atom; and R.sup.4 represents a hydrogen atom or an amino group which may be protected or substituted. These cephalosporins have a broad antibacterial spectrum, are stable against .beta.-lactamase produced by bacteria, have a low toxicity, and are well absorbed when administered orally or parenterally.

Abstract: This invention relates to a 7-amino-3-(pyrazinylmethyl)- or (pyridazinylmethyl)-cephalosporins of the formula: ##STR1## wherein R.sup.1 represents a hydrogen atom or a carboxyl-protecting group; R.sup.2 represents a group of the formula: ##STR2## in which R.sup.6 represents a hydrogen atom, a C.sub.1-5 alkyl group or a di-C.sub.1-5 alkylamino group; R.sup.13 represents a C.sub.1-5 alkyl group; and R.sup.28 represents an amino group.

Abstract: This invention relates to novel 7-(substituted or unsubstituted amino)-3-substituted methyl-.DELTA..sup.3 -cephem-4-carboxylic acids in which a substituted or unsubstituted 1,2,4-triazolyl or 2-(1,2,3,4-tetrazolyl) group attaches to the exomethylene group at the 3-position of the cephem ring through a carbon-nitrogen bond. These cephalosporins are useful intermediates for producing various novel cephalosporins. Also, this invention concerns a process for producing a compound represented by the formula: ##STR1## which comprises reacting a compound represented by the formula: ##STR2## with an optionally substituted triazole or tetrazole in the presence of an acid or a complex of the acid in an organic solvent at 0.degree. to 80.degree. C.

Abstract: This invention relates to a novel process for producing a 2-(2-aminothiazol-4-yl)glyoxylic acid derivative or a salt thereof which are useful in producing a cephalosporin antibiotic, and to intermediates for said derivative and salt and a process for producing the intermediates.

Abstract: The invention relates to antibiotic compounds of the formula: ##STR1## wherein R.sup.1 represents a hydrogen atom or a carboxyl-protecting group; R.sup.2 represents a group of the formula: ##STR2## R.sup.3 represents a hydrogen atom or an alkoxy group; R.sup.4 represents a hydrogen atom or a halogen atom; R.sup.5 represents a hydrogen atom or a protected or unprotected amino group; A represents a group of the formula, --CH.sub.2 -- or a group of the formula, ##STR3## or a group of the formula, ##STR4## and the bond means that the compound may be a synisomer or an anti-isomer or a mixture thereof.

Abstract: This invention relates to a novel process for producing a useful cephalosporin which comprises reacting a thiolo ester compound with a 7-aminocephalosporin in the presence of boron trifluoride or a complex compound thereof. This process enables the cephalosporin to be produced with a high purity in a high yield.

Abstract: This invention relates to a novel process for producing a 2-(2-aminothiazol-4-yl)glyoxylic acid derivative or a salt thereof which are useful in producing a cephalosporin antibiotic, and to intermediates for said derivative and salt and a process for producing the intermediates.

Abstract: Novel cephalosporins which has attached to the exomethylene group at the 3-position of the cephem ring a substituted or unsubstituted aryl, acylamino, aromatic heterocyclic, triazolyl or tetrazolyl group, said aromatic heterocyclic group being attached through a carbon-carbon bond and said triazolyl or tetrazolyl group being attached through a carbon-nitrogen bond, and has the following group attached to the amino group at the 7-position: ##STR1## wherein A represents a group of the formula, --CH.sub.2 -- or a group of the formula ##STR2## in which R.sup.5 represents a hydrogen atom or an alkyl group, and the bond represents syn or anti isomer or their mixture; R.sup.3 represents a hydrogen or halogen atom; and R.sup.4 represents a hydrogen atom or an amino group which may be protected or substituted. These cephalosporins have a broad antibacterial spectrum, are stable against .beta.-lactamase produced by bacteria, have a low toxicity, and are well absorbed when administered orally or parenterally.