Chemistry of the phenoxathiins and isosterically related heterocycles. XI . The synthesis and 13C-NMR spectroscopy of 2-azaphenoxathiin

The synthesis of the 2-azaphenoxathiin ring system via the intermediary 2-azaphenoxathiin 2-oxide is described. Complete assignment of the ¹³C-nmr spectrum is reported, based on the observed heteronuclear ¹H-¹³C spin-couplings of the system and calculated chemical shifts as assignment criteria. The possible relation of the chemical shift of Cα to the dehidral angle of the system is also discussed.