CRYSTALS OF QUINOLINECARBOXYLIC ACID DERIVATIVE SOLVATE

摘要

The invention aims at providing crystals of 6-fluoro-1-methyl-7-[4-(5-methyl-2-oxo-1,3-dioxolen-4-yl)- methyl-1-piperazinyl]-4-oxo-4H-[1,3]thiazeto[3,2-a]quino- line-3-carboxylic acid acetonitrile solvate (compound B) which are useful as an intermediate for producing preferentially III-type crystals of 6-fluoro-1-methyl-7-[4-(5-methyl-2-oxo -1,3-dioxolen-4-yl)methyl-1-piperazinyl]-4-oxo-4H-[1,3]- Thiazeto[3,2-a]quinoline-3-carboxylic acid (compound A). Compound B can be preferentially crystallized from acetonitrile by controlling the supersaturation concentration, and desolvation of the crystals of compound B can give III-type crystals of compound A.