Derived 4H-pyrazole as a reactive intermediate in the transformation of cyclic malonic hydrazide into 1,5-dichloro-1,4-cyclohexadiene through a Diels-Alder reaction with substituted cyclopropenes. AM1 semiempirical and B3LYP density functional theory studies of the cycloaddition reaction of one pyrazole tautomer with cyclopropene

AM1 and B3LYP/6-31G(d) computational studies of the transformation of cyclic malonic hydrazides into derivatives of 1,5-dichloro-1,4-cyclohexadienes were presented. The reactions involved the transformation of cyclic hydrazide into [4H]-pyrazole, the cycloaddition reaction of [4H]-pyrazole with cyclopropene, and finally the elimination of nitrogen from the tricycloadduct obtained through a Diels-Alder reaction. The necessary reaction and structural requirements, from a computational chemistry perspective, were discussed. (C) 1998 Elsevier Science B.V. All rights reserved.