| 摘要 |
PURPOSE:To obtain a new compound useful as an antimicrobial agent, having low toxicity. CONSTITUTION:S-(-)-9-Fluoro-3-methyl-10-(4-methyl or ethyl-1-piperazinyl)-7- oxo-2,3-dihydro-7H-pyrido[1,2,3-de[[1,4]benzoxazine-6-carboxulic acid. This compound is obtained by subjecting a 3-alkyl-7,8-dihalogeno-1,4-benzoxazine derivative shown by formula I and a cyclic amino acid shown by formula II to amide bond reaction to give a diastereomer mixture shown by formula III. The mixture is subjected to fractional crystallization, separated and the product is hydrolyzed to give a 3S-7,8-dihalogeno-3-alkyl-1,4-benzoxazine shown by formula IV, which is allowed to react with a lower alkoxymethylenemalonic acid di-lower alkyl ester and the product is reacted with a polyphosphoric acid, etc., under heating and the product is reacted with an N-lower alkylpiperazine. |
