Thermally Induced [2+2] Cycloadditions of (Benzyloxymethylene)cyclopropane with Alkylidenemalononitriles

Abstract

Abstract The reaction of (benzyloxymethylene)cyclopropane ( 1a ) with alkylidenemalononitriles 2 at ambient pressure afforded the corresponding cyclobutane derivatives 3 in good‐to‐high yields. For example, the reaction of 1a with benzylidenemalononitrile ( 2a ), (2‐naphthylmethylene)malononitrile ( 2e ), and tert ‐butylmethylenemalononitrile ( 2f ) in acetonitrile at 80 °C gave the corresponding cyclobutanes 3a , 3e , and 3f in 96, 96, and 91 % yield, respectively. Control experiments proved that the reaction proceeds via well‐stabilized zwitterionic intermediate 6 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)