Products from Reactions of Methyl (E)-2-Cyano-3-(p-substituted-phenyl)acrylates with 1-Phenyldiazoethane and Cycloreversion of Secondary Pyrazolines

Article abstract of DOI:10.1021/jo00264a025

In dichloromethane, the reaction of methyl (E)-2-cyano-3-(p-substituted-phenyl)acrylates (2) with 1-phenyldiazoethane (1), prepared from 2 molar equiv of acetophenone hydrazone, produced methyl 2-cyano-4-phenyl-4-(p-substituted-phenyl)-2-pentenoates (3), 1-cyano-1-(methoxycarbonyl)-2-methyl-2-phenyl-3-(p-substituted-phenyl)cyclopropanes (4), and 4-cyano-4-(methoxycarbonyl)-3-methyl-3-phenyl-5-(1-phenyl-1-(p-substituted-phenyl)ethyl)-1-pyrazolines (5).Compounds 5 were found to be derived from compounds 3 and 1.Compounds 5 were different from the primary pyrazolines derived from compounds 1 and 2, both in mode of formation and properties.Compounds 5, when decomposed thermally or photochemically, produced the initial olefins 3.This decomposition is an example of "true" cycloreversion.