4‐Diazomethylcoumarins and related stable heteroaryldiazomethanes. Thermal conversion into condensed pyrazoles

Abstract

Abstract 4‐Diazomethyl‐substituted coumarins, 1‐methyl‐2(1 H )‐quinolinones, 1 ‐thiocoumarin and their tricyclic analogs were found to be easily cyclized into the corresponding pyrazole isomers condensed with heteroaromatics. Thermodependent feature of these conversions and the remarkably accelerating effect of the alkyl substituent peri to the diazomethyl group were realized. Some other diazomethyl compounds connected with 2‐pyridinone, 3‐pyrazolone, chromone and 1‐thiochromone were prepared, and their stability and thermal properties were compared.