REACTIVITY OF ETHANEDIYL S,S-ACETALS .3. RING AROMATIZATION IN CYCLOHEXANONE DERIVATIVES - A NOVELTY SYNTHESIS OF 1,4-BENZODITHIANS

Ethanediyl S, S-acetal derivatives of cyclohexanone and substituted cyclohexanones are reported to be fast and smoothly converted into 1, 4-benzodithians, by concurrent aromatization of the six-member ring and expansion of the five-member sulfur-containing one, under simple treatment with bromine in anhydrous chloroform at room temperature. This conversion represents the first hitherto reported synthetic way leading to 1,4-benzodithians (2) variously substituted at the benzenoid ring. The ready availability of these latter makes the 1, 4-benzodithian system itself being regarded as appealing intermediate to obtain, after sulfur replacement or removal, aromatic compounds that cannot be prepared under the usual electrophilic substitution conditions.