Some studies of sulphur containing heterocycles.

The flash vacuum thermolysis and photolysis of a number of cyclic sulphones have been studied with a view to developing these reactions as possible synthetic processes. A number of 2- substituted thietan sulphones have been shown to give the appropriately substituted cyclopropanes in high yields. The corresponding reactions of 3-substituted theitan sulphones are not quite so clean however, and a number of products are formed. Attempts have been made to synthesise sulphoximides based on the thiochroman nucleus; however, without success. The flash thermolyses of thiochroman-4-one sulphones have been studied. The products of these reactions are generally ?,?- unsaturated ketones, and the mechanism has been probed by deuterium labelling experiments. The flash thermolyses of some substituted ?-sultines have been studied in detail. Generally, sulphur dioxide is extruded and the products are derived from the remaining biradical species. In one case however, one of the products is derived from a loss of sulphur monoxide from the starting material. The conformational equilibria of various cis and trans 3-substituted thietan 1-oxides have been studied using n.m.r. spectroscopy and a lanthanide shift reagent technique. In general it has been found that the oxygen atom prefers to adopt an equatorial position in all of the compounds studied.