for the following products
6,7-Difluoro-1-methyl-4-oxo-4H-(1,3)thiazeto(3,2-a)quinoline-3-carboylic acid ethyl ester | Ethyl 6,7-difluoro-1-methyl-4-oxo-1H,4H-(1,3)thiazeto(3,2-a)quinoline-3-carboxylate and Ethyl 6,7-difluoro-1-methyl-4-oxo-4H-[1,3]thiazeto[3,2-a]quinoline-3-carboxylate