INTRAMOLECULAR DIELS-ALDER REACTIONS VIA SULFONE-SUBSTITUTED 3-SULFOLENES

Regiospecific alkylation of the dianion of sulfone-substituted 3-sulfo lenes 1-4 attached an unsaturated alkyl chain at the C2 position to fo rm convenient precursors for IMDA reactions. The substituents on the d iene moiety have a significant effect on the reactivity of the IMDA re actions (H) Me(3)Si > PhS). The stereochemistry of the cyclization rea ction depends on the chain length connecting the diene and dienophile. The hydronaphthalene products 12a and 12b are obtained only in the tr ans form, and the hydroindene products 10 and 11 have predominantly th e trans ring structure. All the products have the useful vinylic sulfo ne structure.