Gas‐phase elimination reactions of 4‐arylideneimino‐1,2,4‐triazol‐3(2H)‐ones and their 3(2H)‐thione analogues

Abstract

Abstract4‐Arylideneimino‐1,2,4‐triazol‐3(2H)‐ones (1–4) and their thio analogues (5–8) were pyrolysed in the gas phase. The reactions were homogeneous and free from catalytic and radical pathways. Analysis of the pyrolysate showed the elimination products to be substituted benzonitriles and the corresponding 3‐hydroxy‐1,2,4‐triazoles and their thio analogues. The kinetic results and product analysis lend support to a reaction pathway involving a six‐membered transition state. At 500 K, the thiooxotriazoles 5–8 were found to be 103‐fold more reactive than the corresponding oxotriazoles 1–4. The reactivities of the 2‐oxotriazoles were compared with those of the substituted 2‐oxopyridine‐3‐carbonitriles. Copyright © 2001 John Wiley & Sons, Ltd.

Synthesis and Antimicrobial Evaluation of Newly Synthesized N,S‐Bisphosphonate Derivatives

“…The required imines 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i , 1j , 1k , 1l , 1m were obtained in high yields (75–85%) from the condensation of the parent 4‐amino‐4 H ‐1,2,4‐triazole‐3‐thiol with the appropriate aromatic aldehydes .…”

“…The required imines 1a-1m were obtained in high yields (75-85%) from the condensation of the parent 4-amino-4H-1,2,4-triazole-3-thiol with the appropriate aromatic aldehydes [20][21][22][23][24].…”

“…New substrates 1b , 1d , 1e , and 1h were prepared according to the reported method . A mixture of the parent 4‐amino‐1,2,4‐triazole‐3‐thiol (10 mmol) and the proper aldehyde 2,5‐dimethoxybenzaldehyde, 2,4‐dinitrobenzaldehyde, 2‐chlorobenzaldehyde, or 2‐bromo‐benzaldehyde (10 mmol) in acetic acid (15 mL) were heated at reflux for approximately 1–2 h (TLC).…”

Regioselective synthesis of 1,2,4‐triazol‐3(2H)‐ones and their 3(2H)‐thiones: Kinetic studies and selective pyrolytic deprotection

“…We have recently demonstrated the potential synthetic utility of thermally labile N-ylidenimino moiety as a protecting group for one of the heterocylic urea and thiourea nitrogens leading to the regioselective substitution of the other nitrogen. Our kinetic studies proved that these N-ylidenimino groups are thermally eliminated via a cyclic six-membered transition state as nitriles (Scheme 1) [2,3]. Application of this technique led to a high regioselective synthesis of the biologically interesting 2-glucosyl-1,2,4-triazole-3(2H)-thiones (2b) (R = tetraacetyl-␤-D-glucosyl) (Scheme 1) [4], related to the broad spectrum antiviral Ribavirin [5].…”

Design, Synthesis and Pharmacological Screening of β-Amino-, Thiadiazole/Thiadiazine-Phosphonate Based Triazole Motifs as Antimicrobial/Cytotoxic Agents

“…Elemental analyses were performed using elementary Analysensysteme GmbH-vario EL III Element Analyzer (Germany). Compounds 4-(4-(dimethylamino)benzylideneamino)-4H-1,2,4-triazole-3-thiol (1) and 4-(4-chlorobenzylidene-amino)-4H-1,2,4-triazole-3-thiol (2) were obtained using the procedures reported elsewhere (19,20). Phosphonyl carbanion reagents: [diethyl (2-amino-2-thioxoethyl)-, diethyl cyanomethylphosphonate, methyl diethyl-, triethyl phosphonoacetate, diethyl (methylthiomethyl)phosphonates, diethyl (methylthioethyl)phosphonate and diethyl 2-methylallylphosphonate] were purchased from Sigma-Aldrich Company (USA).…”