Captodative olefins: methyl 2-aryloxy-3-dimethyl-aminopropenoates and their application in a new synthesis of benzofurans

The β-substituted captodative olefins methyl 2-aryloxy-3-dimethylaminopropenoates 4a–h were synthesized, via aminomethylenation of the corresponding 2-phenoxyacetic esters 9a–h. Lewis acid promoted intramolecular cyclization of alkenes 4 led to benzofurans 7a–h, in an efficient synthetic approach to the benzofuran frame.