Studies with 2-arylhydrazono-3-oxopropanals: Routes for the synthesis of pyridazine-3,4-dicarboxylate and 3,5-diaroyl pyrazoles

Abstract

The title compounds 3a-j were synthesized via coupling of enaminones 2a-d with aromatic diazonium salts. The reaction of 3b-f,h-j with dimethyl acetylenedicarboxylate and triphenylphosphine afforded dimethyl 2-aryl-6-aroyl-2,3-dihydropyridazine-3,4-dicarboxylates 7b-f,h-j. The reaction of 3b,d,f,g with phenacyl bromide afforded 3-aroyl-5-benzoylpyrazoles 9b,d,f,g.,while compound 3i condensed with benzoylacetonitrile to yield pyridazin-6-imine 11.Reaction of 3c-e,h,j with p-toluidine yielded the enamineazo 12c-e,h,j. The structures of 7b,d,i and 9b were confirmed by X-ray crystal structure determination. © ARKAT USA, Inc.