REACTIONS OF PHENYLHYDRAZONES WITH ELECTRON-DEFICIENT ALKENES

Reaction of aliphatic aldehyde phenylhydrazones with methyl acrylate or acrylonitrile gives phenylazoalkanes (1) by an ene reaction. With more electron-deficient alkenes such as methyl vinyl ketone or β-nitrostyrene, Michael reaction at nitrogen occurs followed by cyclization to give pyrazolidines. The reactions of phenylhydrazone monoanions with acrylonitrile take a variety of pathways depending on the counterion. The cuprous salt reacts from carbon to give 1, the lithium salt initiates polymerization, and the diethylaluminum salt alkylates on nitrogen. Copyright © 1979, American Chemical Society. All rights reserved.