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 B3LYPdensity 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 cycli c malonic hydrazides into derivatives of 1,5-dichloro-1,4-cyclohexadienes w ere presented. The reactions involved the transformation of cyclic hydrazid e into [4H]-pyrazole, the cycloaddition reaction of [4H]-pyrazole with cycl opropene, and finally the elimination of nitrogen from the tricycloadduct o btained through a Diels-Alder reaction. The necessary reaction and structur al requirements, from a computational chemistry perspective, were discussed . (C) 1998 Elsevier Science B.V. All rights reserved.