The Diels-Alder reaction of some styrenes and 2,2-dimethylchromenes with acetylenic esters

Abstract

Examples of the Diels-Alder reaction between some derivatives of styrene and of 2,2-dimethylchromene and dimethyl acetylenedicarboxylate and methyl propiolate, leading ultimately to fully aromatic derivatives, are described. Yields are generally low and the synthesis has limited utility. However, the n.m.r, spectrum of the product from acronycine dimethyl acetylenedicarboxylate is such as to establish the angular rather than the linear structure for acronycine.