Chemistry of the phenoxathiins and isosterically related heterocycles. XVI. The synthesis and molecular structure of 3‐azaphenoxathiin: Evidence in support of factors responsible for control of the dihedral angle

Abstract The synthesis of the 3‐azaphenoxathiin ring system and its molecular structure are reported. Based on 13C‐nmr chemical shift additivities associated with the insertion of an annular nitrogen atom and the observed 13C‐nmr shift of Cα, the title compound was predicted to have a dihedral angle θ = 160.2°. The observed dihedral angle from the crystal structure was found to be θ = 167.07° which is in reasonably good agreement with the predicted value. It is proposed that the position of the annular nitrogen atom is solely in‐control of the observed dihedral angle.