Toyama Chemical Co., Ltd.

Narita Hirokazu

Isamu Saikawa

Hiroyuki Imaizumi

Takihiro Inaba

Yasuo Watanabe

Masaru Tai

Hiroshi Sadaki

Hideo Taki

Yoshinori Konishi

Tatsuo Hirakawa

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.

7-(substituted or unsubstituted amino) 3-substituted methyl-.sup.3

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Toyama, Japan

Narita Hirokazu