Facile synthesis of some novel triazolo[3,4-b]thiadiazines and triazolo[4,3-b]tetrazines

Abstract

EXPERIMENTALMelting points were measured on an Electrothermal IA 9000 series digital melting point apparatus. IR spectra were recorded in potassium bromide discs on Pye Unicam SP 3300 and Shimadzu FTIR 8101 PC infrared spectrophotometers. NMR spectra were recorded on a Varian Mercury VX-300 NMR spectrometer operating at 300 MHz ( 1 H NMR) or 75 MHz ( 13 C NMR) and run in deuterated dimethylsulfoxide (DMSO-d6). Chemical shifts were related to that of the solvent. Mass spectra were recorded on a Shimadzu GC-MS-QP1000 EX mass spectrometer at 70 eV. Elemental analyzes were measured by using a German made Elementar vario LIII CHNS analyzer. Hydrazonoyl halides were prepared as previously reported in the respective literature [45]. Synthesisof [1,2,4]triazolo[3,4-b][1,3,4]thiadiazines 5a-e and [1,2,4]triazolo[4,3-b][1,2,4,5]tetrazines 7a-d: General method. A mixture of aminomercaptotriazole 1 (0.144g, 1 mmol) and the appropriate hydrazonoyl halides 2(3) (1 mmol of each) in dioxane (20 mL) containing triethylamine (0.1 g, 1 mmol) was refluxed for 4-8 h. (monitored by TLC). The formed precipitate was isolated by filtration, washed with methanol, dried and recrystallized from the proper solvent to give the respective triazolothiadiazines 5a-e and triazolotetrazines 7a-d. 3-Ethyl-6-methyl-7-(2-phenylhydrazono)-7H-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazine (5a). Yellow

Synthetic Methods and Pharmacological Potentials of Triazolothiadiazines: A Review

“…The reaction of 4-amino-5-substituted-4H-1,2,4-triazole-3-thiols 1 with hydrazonoyl chlorides 2 in refluxing ethanol or dioxane with Et 3 N afforded (7Z)-7- [2-(aryl)hydrazinyli dene]-6-methyl-7H- [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines 3 [6,[9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The produced compounds underwent in vitro testing against 11 candida species and were compared to the conventional medication ketoconazole.…”

“…Scheme 1. Synthesis of - [1,2,4]triazolo [3,4-b] [1,3,4]thiadiazines 3A [6], 3B [9], and 3C [23]. 4-Amino-5-substituted-4H-1,2,4-triazole-3-thiols 1 were treated with ethyl 3-bromo-2-oxopropanoate 4 in ethanol at reflux to afford ethyl triazolothiadiazine-6-carboxylate 5A,B.…”

Vision on Synthetic and Medicinal Facets of 1,2,4-Triazolo[3,4-b][1,3,4]thiadiazine Scaffold

“…Products of the reactions between 4-amino-3-mercaptotriazoles and hydrazonoyl halides are [1,2,4]triazolo[3,4- b ][1,3,4]thiadiazines bearing 2-arylhydrazono group at the 7-position. Abdelrazek et al [ 44 ] reported the facile triethylamine-catalyzed synthesis of 3-ethyl-6-methyl-7-(2-arylhydrazono)-7 H -[1,2,4]triazolo[3,4- b ][1,3,4]thiadiazine derivatives ( 59 ) from the reaction of 4-amino-5-ethyl-3-mercapto-1,2,4-triazole ( 1 ) with variously substituted hydrazonoyl chlorides ( 57 ) in refluxing dioxane. S -alkylated intermediates ( 58 ), generated in situ, are cyclized to afford the desired products ( 59 ) in good yields (80–88%) (Scheme 25 ).…”

Efficient synthesis and In Silico study of some novel pyrido[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidine derivatives

“…In these last two decades, we have launched a program designed to create new easy, synthetic paths to heterocyclic systems that are functionally replaced, using inexpensive laboratory materials with anticipated bioactivities . Under our program, some new pyridine‐fused aza heterocyclic compounds have to be evaluated for biological activity.…”

“…[29][30][31] In these last two decades, we have launched a program designed to create new easy, synthetic paths to heterocyclic systems that are functionally replaced, using inexpensive laboratory materials with anticipated bioactivities. [32][33][34][35][36][37][38][39][40][41][42] Under our program, some new pyridine-fused aza heterocyclic compounds have to be evaluated for biological activity. It was expected that combining a triazole ring with a pyridine and/or a pyrimidine ring in one system could lead to improved biological activity.…”