N-quaternary compounds. Part 52. Photochemically induced valence bond isomerism and rearrangement to pyridinones of thiazolo[3,2-a]pyridinium-8-olate derivatives

Abstract

Irradiation of derivatives of thiazolo[3,2-a]pyridinium-8-olate with a medium pressure Hg lamp resulted in rearrangement to derivatives of the isomeric thiazolo[3,2-a]pyridin-5-ones. Irradiation at 350 nm of 5-methyl-dihydrothiazolo[3,2-a] pyridinium-8-olate gave the valence isomeric structure 6-methyl-2-thia-5-azatricyclo[4.3.0.0^1,5]non-7-en-9-one which on further irradiation with the medium pressure Hg lamp yielded the corresponding rearranged dihydrothiazolo[3,2-a]pyridin-5-one.