Heterocyclic rearrangements. Part VI. Structure and stereochemistry of a sulphur-bridged tetrahydroazepine and derived sulphoxides, by X-ray crystallography and nuclear magnetic resonance spectroscopy

Abstract

The structure and stereochemistry originally proposed for dimethyl 1,3-dimethyl-2-aza-8-thiabicyclo[3,2,1]oct-3-ene-4,7-dicarboxylate (I) have been confirmed by X-ray diffraction analysis. Assignments of the n.m.r. signals for the 6- and 7-protons in (I) have been reversed as a result of a study of a specifically deuteriated derivative. Reduction of (I) to the hydroxy-ester (IV) is described. The configuration of the two diastereoisomeric sulphoxides derived from (I) has been established. Their thermal equilibration, thermolysis to methyl 2-methyl-pyrrole-3-carboxylate, and oxidation to the corresponding epoxide (XI) are described.