(-)-ethyl 9,10-difluoro-2,3-dihydro-3-hydroxymethyl-7-oxo-7H-pyrido<1,2,3-de><1,4>benzoxazine-6-carboxylate

(+/-)-ethyl 9,10-difluoro-2,3-dihydro-3-(3,5-dinitrobenzoyloxy)methyl-7-oxo-7H-pyrido<1,2,3-de><1,4>benzoxazine-6-carboxylate

(S)-ethyl 3-(((3,5-dinitrobenzoyl)oxy)methyl)-9,10-difluoro-7-oxo-3,7-dihydro-2H-[1,4]oxazino[2,3,4-ij]quinoline-6-carboxylate