Reaction of primary thioamides withp-toluenesulfinic acid

The conversion of thioamides to the corresponding 1,2,4-thiadiazoles occurs upon heating primary thioamides with formaldehyde andp-toluenesulfinic acid in water instead of the formation of N-(tosylmethyl)thioamides.M. V. Lomonosov State Academy for Fine Chemical Technology, 117571 Moscow, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 412–415, Marhc, 1997.     

Green synthesis of 1,2,4-thiadizoles from thioamides in water using molecular oxygen as an oxidant

We present here an efficient green process for the synthesis of 1,2,4-thiadiazoles via iodine-catalyzed,oxidative dimerization of thioamides in water using molecular oxygen as a terminal oxidant. Under the optimized reaction conditions, aryl thioamides produced 3,5-diaryl-1,2,4-thiadiazoles in good to excellent yields. Alkyl thioamides and substituted thioureas could also provide corresponding 1,2,4-thiadiazole products.     

tert-Butyl nitrite induced radical dimerization of primary thioamides and selenoamides at room temperature

A simple and efficient method for the dimerization of primary thioamides into 1,2,4-thiadiazoles using tert-butyl nitrite is described. The optimized condition was also found to be suitable for the dimerization of benzoselenoamides into 1,2,4-selenadiazoles. All the reactions proceed smoothly at room temperature and gave the desired products in excellent yields in a short span of time.     

A Simple and Convenient Method for the Synthesis of 3,5‐disubstituted 1,2,4‐thiadiazoles via Oxidative Dimerization of Primary Thioamides

A simple and efficient protocol has been developed for the preparation of 3,5‐diaryl‐1,2,4‐thiadiazoles in high yields through the oxidative dimerization of primary thioamides in aqueous medium at room temperature.     

Annelation of the thiazole ring to 1,2,4-triazines by tandem AN—AN or SN H—SN H reactions

The reactions of 3-aryl-1,2,4-triazines with aromatic thioamides and 4-arylthiosemicarbazides in acetic anhydride at room temperature afforded cyclic products of the tandem nucleophilic addition reactions, viz., tetrahydrothiazolo[4,5-e]-annelated 1,2,4-triazines, in good yields. The latter underwent aromatization in the presence of potassium permanganate.     

An unexpected synthesis of 3,5-diaryl-1,2,4-thiadiazoles from thiobenzamides and methyl bromocyanoacetate

Aryl thioamides undergo very rapid condensation in the presence of methyl bromocyanoacetate to provide quantitative yields of 3,5-diaryl-1,2,4-thiadiazoles with an easy work-up and a high degree of product purity. The method can be scaled up with no loss in efficiency.     

Solution and solid-supported synthesis of 3,4,5-trisubstituted 1,2,4-triazole-based peptidomimetics

[reaction: see text] 3,4,5-Trisubstituted 1,2,4-triazoles were synthesized in solution from various thioamides and hydrazides in smooth experimental conditions leading to peptidomimetic scaffolds. This strategy was found to be compatible with the usual peptide synthesis protecting groups. This methodology was then applied on solid support by anchoring alpha-amino acids through their amino function to an activated carbonate resin.     

TCT‐DMSO/[bmim]BF4: A novel promoter system for the synthesis of 3,5‐diaryl‐1,2,4‐thiadiazoles at ambient temperature

An efficient and practical procedure for direct synthesis of 3,5‐diaryl‐1,2,4‐thiadiazoles by thioamides with 2,4,6‐trichloro‐1,3,5‐triazine (TCT) and dimethylsulfoxide using 1‐butyl‐3‐methylimidazolium tetrafluoroborate as an eco‐friendly reaction medium under ambient temperature is described. This protocol can be considered as a new procedure for 3,5‐diaryl‐1,2,4‐thiadiazoles synthesis. J. Heterocyclic Chem., (2010).     

The reactions of C-methylheterocycles with thionyl chloride. Part 3. The transformation of some five-and six-membered heterocycles

Reactions of various five-and six-membered C-methylheterocycles with hot thionyl chloride gave chlorothio intermediates which were not characterized but which gave 1,2,4-thiadiazole derivatives when reacted with amidines and gave thioamides when reacted with amines. When 2,3-dimethyl-6-ethoxycarbonylimidazo-[4,5-b]pyridine ( 26 ) was treated with thionyl chloride a trisulphane 27 was isolated.     

Azo-coupling of pyrazole-3(5)-diazonium chlorides with cyanothioacetamide: a convenient synthesis of pyrazolo[5,1-c][1,2,4]triazine-3-carbothioamides

Cyanothioacetamide reacts with pyrazole-3(5)-diazonium chlorides to afford pyrazolo[5,1-c][1,2,4]triazine-3-carbothioamides 5. The latter can be oxidized with H₂O₂ to give either pyrazolo[5,1-c][1,2,4]triazine-3-carboxamides or 1,2,4-thiadiazole derivatives, depending on the reaction conditions. The Hantzsch-type reaction of thioamides 5 with α-bromo ketones leads to 3-(thiazol-2-yl)pyrazolo[5,1-c][1,2,4]triazines.     

O,O-Diethyl dithiophosphoric acid mediated direct synthesis of thioamides from aldehydes and ketones

A general and convenient method for a one-pot conversion of aldehydes and ketones into thioamides has been developed. The protocol involves oximation of aldehydes and ketones followed by deoxygenative thioamidation of oximes with O,O-diethyl dithiophosphoric acid which acts as an acid as well a source of sulfur. The method is operationally simple, high yielding, and also applicable to the conversion of amides and nitriles into the corresponding thioamides.     

The cyanoethylation reaction and electronic structure of N-phenylated thioamides of the 1,2,4-triazole and tetrazole series

The cyanoethylation reactions of 1-phenyl-1,2,4-triazoline-3-thione (I) and of 1-phenyl-1,2,4,-triazoline-5-thione (II) have been studied. The cyanoethylation of I forms only S-cyanoethyl derivates,and the cyanoethylation of II only N-cyanoethyl derivatives. The structures of the reaction products were confirmed by UV spectroscopy and by independent synthesis. On the basis of a quantum-mechanical analysis of the compounds, their tautomeric forms, and the assumed primary reaction products, it has been concluded that the mechanism of the cyanoethylation and transcyanoethylation reactions of these heterocyclic thioamides is a common one.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 8, pp. 1138–1144, August, 1970.     

Conversion of Thioamides into Their Corresponding Oxygen Analogues Using Silver Carbonate Supported on Celite

Silver carbonate supported on celite (Ag 2 CO 3 /Celite) is used as a mild heterogeneous reagent for conversion of a variety of thioamides into their corresponding amides in acetonitrile at room temperature.     

Silver(I)-promoted conversion of thioamides to amidines: divergent synthesis of a key series of vancomycin aglycon residue 4 amidines that clarify binding behavior to model ligands

Development of a general Ag(I)-promoted reaction for the conversion of thioamides to amidines is disclosed. This reaction was employed to prepare a key series of vancomycin aglycon residue 4 substituted amidines that were used to clarify their interaction with model ligands of peptidoglycan precursors and explore their resulting impact on antimicrobial properties.     

A convenient method for the selective reduction of amides to amines

A variety of amides have been selectively reduced to the corresponding amines via conversion to their thioamides and treatment with triethyloxonium tetrafluoroborate followed by sodium borohydride. This procedure is compatible with isolated and conjugated double bonds, esters, intro groups, and sulfonamides.     

Conversion of Thioamides into Their Corresponding Oxygen Analogues Using Silver Carbonate Supported on Celite

Silver carbonate supported on celite (Ag₂CO₃/Celite) is used as a mild heterogeneous reagent for conversion of variety of thioamides into their corresponding amides in acetonitrile at room temperature.

     

Efficient Uncatalyzed Conversion of Primary and Secondary Thioamides into 1-Substituted, 5-Substituted, 1, 5-Disubstituted and Annulated Tetrazoles

Abstract

Unprecedented high-yield simple and mild conversion of primary aliphatic and aromatic thioamides into 5-substituted tetrazoles on treatment with a combination of tetrachlorosilane and sodium azide in refluxing acetonitrile has been achieved. Secondary acyclic, cyclic, and heterocyclic thioamides could also be transformed in high yields into 1-substituted, 1,5-disubstituted, or annulated tetrazoles under the same reaction condition.

GRAPHICAL ABSTRACT      

Pd-catalyzed allylic alkylation of thioamides

This work describes the first Pd-catalyzed allylic alkylation of thioamides. Various thioamides were efficiently α-allylated in high yields and with excellent selectivity for monoallylation under mild reaction conditions. The process not only provides a facile method for the synthesis of functionalized thioamides, but also presents a useful transformation for synthetically important thioamides.     

Synthesis of 3-Azido-5-amino-1,2,4-triazole

3-Azido-5-amino-1,2,4-triazole was obtained from 3,5-diamino-1,2,4-triazole in two ways: by partial diazotization-substitution directly in the substrate or at its primarily nitrosation, and also with the use of direct or indirect protection of an amino group with subsequent conversion into azido compound followed by deprotection.     

Synthesis and some reactions of hexahydro-1,2,4-triazine-3,6-dione

The synthesis of hexahydro-1,2,4-triazine-3,6-dione by hydrogenolysis of 1,2-dibenzylhexahydro-1,2,4-triazine-3,6-dione is reported. Ring contraction of the former dione to 3-amino-2,4-imidazolidinedione is discussed. The preparation of the 1- and 2-benzyl derivatives of hexahydro-1,2,4-triazine-3,6-dione and their conversion to the unsubstituted product are also described.