STUDIES ON STRUCTURE OF LIGHT DEGRADATION PRODUCTS OF O-7H-PYRIDO[1,2,3-DE][1,4]BENZOXAZINE-6-CARBOXYLIC ACID (T-3761) IN AQUEOUS-SOLUTION AND SOLID-STATE

The structures of light degradation products of(-)-(S)-10-(1-aminocycl opropyl)-9 oro-3-methyl-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de] [1,4] be nzoxazine-6-carboxylic acid (T-3761) in aqueous solution and in the so lid state were investigated. In aqueous solution, ten products were de tected using HPLC and in the solid state, one main product was detecte d. All these light degradation products were isolated and their struct ures were elucidated. It was revealed that in almost all light degrada tion products only the 1-aminocyclopropyl side chain at the 10-positio n of T-3761 is changed to various structures by light oxidation. Surpr isingly we found a unique light degradation product, in which carboxyl ic acid at the 6-position of T-3761 is changed to the hydroxy moiety.