Studies on Heterocyclic Compounds. XIV. 1, 3-Dipolar Cycloaddition Reaction of Dimethyl Acetylenedicarboxylate with Phenylhydrazones

Abstract

1, 3-Dipolar cycloaddition of aldehyde hydrazones with dimethyl acetylenedicarboxylate without solvent gives rise to dimethyl 1, 3-diphenylpyrazole-4, 5-dicarboxylate, and in some cases trimethyl 1-phenylpyrazole-3, 4, 5-tricarboxylate as a by-product. In case of p-chloro- and p-methoxy-benzaldehyde phenylhydrazone, dimethyl 1-phenyl-3-(p-substitutedphenyl) pyrazoline-4, 5-dicarboxylate is formed. In dimethylformamide as a solvent, the reaction gives the same product in a similar yield. Although, when ethanol is used as a solvent, a small amount of the product is formed.