Synthesis and Reactivity of Enaminones: Synthesis of Some 1,3,4‐Thiadiazole Linked to Pyrazole, Pyridine, Benzimidazolopyrimidine, Pyrazolopyrimidine, Pyrazolotriazine and Triazolotriazine Derivatives

Abstract

1,3,4‐Thiadiazole‐enaminone (6) was synthesized via reaction of the benzamide (5) with DMF‐DMA. The simple thiadiazole‐enaminone (6) was used as a synthetic precursor for the synthesis of a wide variety of new heterocyclic compounds, including the 5‐substituted‐1,3,4‐thiadiazole derivatives (7), (8), (16), (17) and (18), which were obtained via reactions of (6) with nitrogen nucleophiles. Also, reactions of enaminone (6) with carbon nucleophiles afforded the respective 1,3,4‐thiadiazoles (10a,10b). Diazotization of the benzamide (20) with the heteroaromatic amine salts gave the hydrazone derivatives (21) and (22). Cyclization of the latter hydrazones yielded the corresponding pyrazolotriazine and 1,2,4‐triazolotriazine derivatives (23) and (24), respectively. All newly synthesized compounds were elucidated by considering the data of both elemental and spectral analysis.

Synthesis of Pyrazolo[1,5‐a][1,3,5]triazine, Pyrazolo[1,5‐a]pyrimidine, and Imidazo[1,2‐b]pyrazole Derivatives Based on Imidazo[2,1‐b]thiazole Moiety

“…In view of the aforementioned biological importance and in continuation of our interest in the synthesis of various heterocycles and its pharmacological properties , we report herein a facile synthetic strategy for synthesis of pyrazole, pyrazolo[1,5‐ a ][1,3,5]triazine, pyrazolo[1,5‐ a ]pyrimidines, imidazo[1,2‐ b ]pyrazole derivatives, and Schiff‐based derivatives linked to imidazo[2,1‐ b ]thiazole. The biological activities of the synthesized products will be reported in the extended work.…”