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

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 13C‐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.

Electrophilic cleavage of cyclopropanes. IV. The reaction of 2-nitrobenzenesulphenyl chloride with tetracyclo[3.2.0.02,7.04,6]heptane in methanol and acetic acid: the crystal structure of exo-3-(2′-nitrophenylthio)-exo-5-methoxytricyclo[2.2.1.02,6]heptane, C14H15NO3S

“…There is no doubt therefore that the strength of the interaction depends on the nature of the substituents on S. This was demonstrated clearly by Kilmin and Pirkinyi (18) (19). The energetic favourability of the above interaction between sulphur and an oxygen atom of the ortho-nitro substituent is corroborated both here and elsewhere by use of carbon-13 nmr spectroscopy (18,(20)(21)(22) to exist in the solution phase and thus is not a manifestation of the conformational changes often required during crystallization to give the energetically most stable packing arrangement in the crystal stucture.…”

Chemistry of the phenoxathiins and isosterically related heterocycles. XV. Synthesis of 1‐nitrophenoxathiin and the relation of the 13C‐Nmr chemical shift of the alpha‐carbon to the dihedral angle

“…2 The calculated chemical shift of this resonance was adjusted for the sulfur-nitro interaction as previously described (5).…”