THIOCARBONYLS .X. ISOMERIC 2,4,6-TRIS(HALOPHENYL)-1,3,5-THIANES

Nine pairs of isomeric 2,4,6‐tris(halophenyl)‐1,3,5‐trithianes have been assayed in the crude state by n.m.r. techniques, and separated and purified by chromatography. Contrary to previous reports, the α‐(cis, trans)‐isomers are the major products in most cases. These compounds are shown to exist as puckered chair trithiane structures, even in the more hindered α‐(cis, trans)‐o‐halophenyl cases, by the clear resolution of axial and equatorial trithiane ring protons in a ratio of 2:1. An o‐halogen on an axial phenyl group in the α‐isomers causes the aromatic group to exert an anisotropic deshielding effect on adjacent axial protons, so as to cause the axial and equatorial proton peaks to appear as a singlet in some solvents. Melting point differences, in several cases quite large, from those previously reported have been observed for six of the eighteen triaryltrithianes reported. Copyright © 1969 Journal of Heterocyclic Chemistry