Chemistry of the phenoxathiins IV. Synthesis of 9‐substituted 1 ‐azaphenoxathiins

Abstract

Abstract In an extension of recently reported syntheses of the I‐azaphenoxathiin nucleus as well as several 7‐substituted analogs, the synthesis of several 9‐substituted members of this series is now reported. In addition, the first 13 C‐nmr spectral evidence of an interaction between a sulfur atom and the oxygen of an ortho ‐nilro group which has been previously observed only in X‐ray erystallographic studies is also described. The possible consequences of this interaction on the reaction pathway leading to the cyclization of the 9‐substituted J‐azaphenoxathiin nucleus is also presented.