Unusual reactivity of thiosemicarbazides towards 2,3-diphenylcyclopropenone: synthesis of new pyridazinethiones and 1,2,4-triazolo[4,3-b]pyridazinethiones

Abstract

New pyridazinethiones and 1,2,4-triazolo [4,3-b]pyridazinethiones have been obtained during the reaction of thiosemicarbazide and its 1,4-disubstituted derivatives with 2,3-diphenylcyclopropenone. The reaction of this cyclopropenone with two equivalents of thiosemicarbazide afforded the corresponding 1,2,4-triazolo [4,3-b]pyridazinethiones. However, the reaction of Nsubstituted hydrazino derivatives of thiosemicarbazides with the cyclopropenone occurs with stoichiometric amounts of the starting materials to produce pyridazinethiones. The reaction mechanism, in both cases, was described as a formal [3+3]-cycloaddition.

Unusual Reactivity of 2,3-diphenylcyclopropenone towards N-imidoylthioureas; Facile Synthesis of 3-aryl-2,5,6-triphenylpyrimidin-4(3H)-one (PART III)

“…16,17 The synthesis of pyridazinethiones and 1,2,4-triazolo [4,3b]pyridazinethiones from the reaction of thiosemicarbazides with 1 has been described previously. 18 Moreover, we have isolated (E/Z)-3-(aroylthioureido)-2-phenylcinnamates from the reactions of N-substituted aroylthioureas with 1 in acetic acid. That abnormal activity was described as due to nucleophilic addition of N 3 followed by hydrolysis, ring opening and oxidation processes.…”

Convenient diastereoselective synthesis of annulated 3-substituted-(5S*,6S*,Z)-2-(2-(2,4-dinitrophenyl)hydrazono)-5,6-diphenyl-1,3-thiazinan-4-ones

“…The reaction of 1 with various aldehyde 4-phenylthiosemicarbazones in acetic acid provided, pyrrolo [2,1-b]oxadiazoles [14]. Also, thione derivatives such as 2,4-disubstituted thiosemicarbazides (4, R = C 6 H 5 ; C 6 H 5 CH 2 ) reacted with 1 via a nucleophilic attack of terminal-NH 2 of 4 on the carbonyl group of 1, afforded pyridazines 5 (Scheme 1) [15].…”

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

“…Besides, Aly et al reported on the synthesis of various thiazin-4-ones from the reactions of aroylthioureas (ArCONHCSNHR) with dimethyl acetylenedicarboxylates [18]. In addition, thiosemicarbazides show unusual reactivity towards 2,3-diphenylcyclopropenone, giving a variety of pyridazinethiones and 1,2,4-triazolo [4,3-b]pyridazinethiones [19]. Recently, we have utilized microwave irradiation to assist the synthesis of triazoloquinazolinones and benzimidazoquinazolinones Vol 45 [20].…”