Easy access to (E,Z)-β-nitro-α,β-olefinated hydrazones, 6-oxo-1,6-dihydropyridazines, and 4-chloro-1-aminopyrroles by domino reactions of 1,2-diaza-1,3-butadienes with halogen-coactivated methylene or methine compounds

In the presence of a catalytic amount of sodium methoxide, 1-aminocarbonyl-1,2-diaza-1,3-butadienes react with bromonitromethane to give stereos electively beta-nitro-alpha,beta-olefinated hydrazones as E,Z stereoisomers. In the presence of a stoichiometric amount of sodium hydride, the same substrates with dialkyl halomalonates furnish the expected alpha,beta-olefinated hydrazones, and in the presence of a stoichiometric amount of sodium hydroxide, the unexpected dialkyl 3-methyl-6-oxo-1,6-dihydropyridazine-4,5-dicarboxylates are obtained in one pot by a domino process concluding in a [4 + 2] cyclization. alpha,beta-Olefinated hydrazones have been shown to be the possible intermediates in the formation of 1,6-dihydropyridazine derivatives. The domino reaction of 1-aminocarbonyl-1,2-diaza-1,3-butadienes with alpha,alpha-dichloroacetophenone produces directly alkyl 4-chloro-2(chloromethyl)-5-phenyl- or alkyl 4-chloro-2( methoxymethyl)-5-phenyl-1N-aminopyrrole-3-carboxylates as a consequence of [3 + 2] cyclization and chlorine transfer.