Some uses of cyclic sulphones in organic synthesis
The thermolysis and photolysis of a number of cyclic sulphones has been studied, with a view to developing these reactions as possible synthetic processes. Some substituted dihydronaphthothiophene sulphones were prepared and those containing a pent-4-ene sidechain successfully underwent intramolecular Diels-Alder cyclisations. 2-Phenylthietan was prepared by a new route and the preparation and pyrolysis of some 2-phenylthietan 1,1-dioxide derivatives was studied. Some 2-(alkan-1-o1) 3,3-dimethylthietan sulphones were prepared and the dehydration of these, with a view to preparing alk-1-ene derivatives, was studied. Phosphorus oxychloride in pyridine was the most successful of those reagents tried. The alk-1-ene derivatives were shown to have unusual thermal behaviour, when they ring-expanded to their respective sultines under flash vacuum thermolysis conditions. The use of 3,3-dimethylthietan 1,1-dioxide as a starting material for a new route to chrysanthemates has been studied. Methyl-trans-chrysanthemate was eventually identified as one of the products after a 4-step synthesis from this sulphone. A number of cyclic sulphides were prepared using phase transfer catalysis.