Conventional and microwave irradiation assisted synthesis of new 1,2,4‐triazepine‐3‐thiones

Abstract

New 1,2,4‐triazepine‐3‐thiones have been obtained during the respective reactions of N‐substituted‐hydrazino carbothioamides with dimethyl acetylenedicarboxylate and dibenzoyl acetylene under prolonged reflux in acetic acid and/or DMF. However, the reaction of the starting materials in DMF under microwave irradiation afforded the same products in higher yields within a few minutes.

The Reactivity of Dimethyl Acetylenedicarboxylate and Heterocyclization of Hydrazinecarbothioamides to 1,3‐Thiazolidin‐4‐ones

“…We report here the results of our investigations on the reaction of hydrazinecarbothioamides 6a , 6b , 6c , 6d , 6e with 2 . These results are compared with those obtained in Scheme . As shown in Scheme , the synthesis of thiazolidin‐4‐ones 7 and 8 was simply affected by the nucleophilic active centers in hydrazinecarbothioamides 6a , 6b , 6c , 6d , 6e and an electrophilic acetylenic ester (DMAD, 2 ).…”

“…Methyl [3‐aryl‐4‐oxo‐1‐(phenylthiocarbamoyl)‐4,5‐dihydro‐pyrazol‐5‐ylidene]ethanoates were formed from the reaction of arenealdehyde 4‐phenylthiosemi‐carbazones with dimethyl acetylenedicarboxylate (DMAD, 2 ) , whereas 1,2,4‐triazepine‐3‐thiones 4a , 4b , 4c and 5a , 5b , 5c , 5d were formed via conventional and microwave irradiation of 4‐substituted thiosemicarbazides 1a , 1b , 1c and 2,4‐disubstituted thiosemicarbazides 3a , 3b , 3c , 3d with DMAD, 2 (Scheme ) .…”

Utility of Acetylenedicarboxylate in Organic Synthesis

“…Microwave irradiation or refluxing in acetic acid equimolar amounts of 4‐substituted thiosemicarbazides 166b , 166c , 166d and DMAD ( 1a ) leads to the formation of 5‐oxo‐3‐thioxo‐1,2,4‐triazepine‐7‐carboxylic acid methylester derivatives 204a , 204b , 204c and 205a , 205b , 205c (Scheme ) .…”

Hydrazinecarbothioamide group in the synthesis of heterocycles

“…76 Spectroscopic data excluded the formation of the regio-isomeric heterocycle 132 (Scheme 56). N-Imidoylthioureas (133, analogous to thiocarbohydrazides) reacted with DMAD (128) to form 1,3,5-thiadiazepines 134a-e (Scheme 57).…”