DIELS-ALDER REACTIONS OF 1,1-BIS(METHYLTHIO)ETHENE WITH PYRAN-2-ONES

Bis(methylthio)ethene has been shown to undergo Diels-Alder cycloaddit ion reactions with a range of simple and aryl-fused pyran-Zones. These reactions can be brought about under either high-temperature or high- pressure conditions. These reactions are all regiospecific and in each case only a single product is isolated, either the initial bridged ad duct or an aromatized product generated through decarboxylation. Altho ugh this dienophile is less reactive than the corresponding oxygen ana logue it is still possible for cycloaddition chemistry to compete effe ctively with decarboxylation chemistry.