Daiichi Pharmaceutical Co., Ltd.

Tazuo Uemura

Atsushi Sato

Yukio Sato

Youichi Kimura

Katsuhiro Kawakami

Yusuke Yukimoto

Keiji Uchiyama

Norimasa Mikata

Tatsuro Sumikawa

A method for selectively obtaining any one of an anhydrate, a 1/2 hydrate, a 1 hydrate, and a 3/2 hydrate of 7-�(7-(S)-amino-5-azaspiro�2.4!heptan-5-yl!-8-chloro-6-fluoro-1-�(1R,2S)-2 -fluorocyclopropyl!-4-oxo-1,4-dihydroquinoline-3-carboxylic acid is disclosed, comprising treating the compound in an aqueous solvent or water or recrystallizing the compound from an aqueous solvent or water.

Crystals of antimicrobial compound

A process for selectively producing an (S)-9-fluoro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-2,3 -dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid hemihydrate or monohydrate as depicted below, which comprises controlling the water content of an aqueous solvent in which an (S)-9-fluoro-3-methyl-10-(4-methyl-1-piperazin -yl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzoxazine-6-carboxylic acid is dissolved during a crystallization. ##STR1##

Process for selectively producing an

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Tokyo, Japan

Tazuo Uemura