Reaction of Terminally Alkyl-Substituted Oxy Dienes with Tetracyanoethylene and Other Acceptors

Abstract

The 4,4-dimethyl-substituted oxy dienes (4), (19) and (20) did not undergo cycloaddition to 1,4-quinonoid dienophiles, for steric reasons, but all reacted with tetracyanoethylene to give [4+2]- or [2+2]-adducts. Unlike the 1-oxy diene (4), the 2- and 3-oxy systems (19) and (20) did not show hydrogen-transfer chemistry towards quinones. The individual components of isomeric pairs of dienes (8), (9) and (19), (21) were differentiated by differing reactivity towards cycloaddition.