Synthesis of hexahydropyridazin-3-ones by reactions between donor-acceptor cyclopropanes and phenylhydrazine

The nickel perchlorate-initiated reaction between dimethyl esters of 2-aryl- and 2-styryl-substituted cyclopropane-1,1-dicarboxylic acids and phenylhydrazine proceeded with opening of the cyclopropane ring and formation of a mixture containing acyclic and cyclic products: [2-(1-phenylhydrazinyl)alkyl]malonates and 1-phenylhexahydropyridazin-3-ones. Reaction conditions were found for preparative synthesis of polyfunctional hexahydropyridazin-3-ones. Unlike the other starting materials, 2-( p- methoxystyryl)-substituted cyclopropane reacted with the terminal NH2 group of phenylhydrazine, resulting in the formation of 1-(phenylamino)pyrrolidin-2-one.