Taiho Pharmaceutical Company Limited

Tomoyasu Ohno

Shingo Yano

Kazuo Ogawa

Shozo Yamada

Tetsuhiko Shirasaka

Hideo Tanaka

Sigeru Torii

Makoto Kajitani

Motoaki Tanaka

Hiroyuki Kawamura

Akira Nakai

Noriyuki Yamamoto

Shinichi Watanabe

Hirofusa Ajioka

Hisashi Ohbayashi

Haruo Yamada

Kosuke Fujiwara

Oxazolidine derivatives and pharmaceutically acceptable salts thereof

1-phenylpyrrolidone derivatives having optical activity, intermediate

Benzothiadiazine derivatives

Disclosed are 2.beta.-substituted-methylpenicillanic acid compounds of the formula ##STR1## wherein n is 0, 1 or 2; and ##STR2## is monocyclic or bicyclic heterocyclic ring group which has 2 to 4 nitrogen atoms as hetero atom in its ring structure and which may be optionally substituted with alkyl, alkoxycarbonyl, phenyl, formyl or benzyloxycarbonyl optionally having alkyl, nitro or a halogen atom on the benzene ring, with the proviso that said heterocyclic ring group is not 1,2,3-triazol-1-yl; or salts or esters thereof. These compounds are useful as .beta.-lactamase inhibitor.

2.beta.-Substituted-methylpenicillanic acid derivatives, and salts and

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Hannou, Japan

Tomoyasu Ohno