Microwave-accelerated Wittig olefination of β-chloroacroleins

The first microwave assisted Wittig reactions of β-chloroacroleins with a stabilized ylide are described here. A combination of sodium ethoxide and toluene was found to be optimum and using this reaction condition a number of alkenyl-substituted benzopyran/benzo[b]oxepine/2-chromenone derivatives were prepared within few minutes. The microwave mediated process was found to be comparable with the conventional Wittig reaction in terms of product yields. All the products isolated were found to have E-geometry around the Cdouble bond; length as m-dashC bond.