Behavior of N,S-divinyl-2-mercaptobenzimidazole in the thiylation reaction

N,S-Divinyl-2-mercaptobenzimidazole reacts with thiols under free-radical initiation conditions at both vinyl groups to giveβ-addition products, whereas it reacts with sulfur dioxide to give a stable complex. N-Vinylbenzimidazole-2-thione was obtained by heating the divinyl derivative of benzimidazole-2-thione in the presence of a mercaptan without a catalyst. The former on reaction with thiols under the influence of azobisisobutyronitrile readily forms N-(β-alkylthio)ethylbenzimidazole-2-thiones; in the presence of ionic catalysts, N-(α-alkylthio)ethylbenzimidazole-2-thiones are formed.     

Composés sulfurés hétérocycliques. CII. Action de l'hydroxylamine sur les dihydro-1,2 benzothiazine-3,1 thiones-4

Hydroxylamine reacts with 1-alkyl-1,2-dihydro-3,1-benzothiazine-4thiones ( 1 ), giving 1-alky1-3-hydroxy-2,3-dihydro-1H-quinazoline-4-thiones ( 2 ). The same reagent, in neutral medium, converts 1-aryl-1,2-dihydro-3,1-benzothiazine-4-thiones ( 3 ) into 1-aryl-4-hydroxyimino-1,4-dihydro-2H-3,1-benzothiazines ( 4 ). In acidic medium, the same starting materials lead to 1-aryl-3-hydroxy-2-3-dihydro-1H-quinazoline-4-thiones ( 5 ). genrally with some quantity of the isomer 4 . Thiones 2 and 5 , as well as oximes 4 , heated at 200°, decomopose, yielding, in varying proportions, 1H-quinazoline-4-thiones ( 6 or 7 ), 1H-quinazoline-4-ones ( 9 ) and 2,3-dihydro-1H-quinazoline-4-thiones ( 11 ). Reacting with methyliodide, 1H-quinazoline-4-thiones ( 7 ) give 4-methylthioquinazolin-1-ium iodidies ( 12 ) which can be hydrolysed into 1H-quinazolin-4-ones ( 9 ). The latter are also obtained by reacting benzonitrile N-oxide with the corresponding thiones. 1-Aryl-1 H-quinazoline-4-thiones ( 7 ) react readily with nitrogen nucleophiles XNH₂ to give 1-aryl-4-imino-1,4-dihydro-quinazolines diversely substituted on the imino group. While thiones 7 are S- methylated by methyl iodide, the corresponding 1-aryl-1H-quinazolin-4-ones (9), with the same reagent, ungergo a N-methylation, yielding 1-aryl-3-methyl-4-oxo-3,4-dihydroquinazolin-l-ium iodides ( 18 ). Structure have been confirmed by uv, ir and nmr spectra.     

A facile synthesis of 1-alkylthio and acylthio-2,3-dihydro-1H-naphtho[2,1-b]thiopyrans and 4-alkylthio and acylthio-3,4-dihydro-2H-naphtho[1,2-b]thiopyrans

The reaction of 3-(2-naphthylthio)propionaldehyde ( 3 )and its (1-naphthylthio)isomer (7)with a variety of thiols and thio acids in the presence of sulfuric acid at room temperature afforded 1-alkylthio and acylthio-2,3-dihydro-1H-naphtho[2,1-b]thiopyrans 5 and 4-alkylthio and acylthio-3,4-dihydro-2H-naphtho[1,2-b]thiopyrans 9 in excellent yield.     

The Action of Carbon Disulfide and Sulfur on Enamines,Ketimines, and CH Acids

The reaction of sulfur, carbon disulfide, and enamines at room temperature leads mainly or exclusively to 3H-1,2-dithiole-3-thiones; these are occasionally accompanied by 2H-1,3-dithiole-2-thiones, which can also be prepared by a modified procedure. Many enamines react with sulfur at room temperature to form thioamides. At about 50°C, enamines of acetophenone give 2-benzylidene-4-phenyl-2H-1,3-dithiol. The action of isothiocyanates and sulfur on enamines leads to the formation of thiazolidine-2-thiones. 2H-Thiopyran-2-thiones can be prepaAred from enamines or dienamines with carbon disulfide at room temperature. The reaction of ketimines (Schiff bases) with carbon disulfide and sulfur yields 3H-1,2-dithiole-3-thiones or isothiazoline-5-thiones. The reaction of alkynes with sulfur and carbon disulfide leads to 2H-1,3-dithiole-2-thiones. Nitriles containing active methylene groups react with carbon disulfide and sulfur to form 5-amino-3H-1,2-dithiole-3-thiones. When isothiocyanates are used instead of CS₂, the reaction leads to δ⁴-4-amino-thiazoline-2-thiones.     

Intramolecular rearrangement of substituted l,2,3,6-tetrahydropyrimidine-2-thiones

The intramolecular rearrangement of substituted 1,2,3,6-tetrahydropyrimidine-2-thiones to the isomeric 2-alkyl(aryl)amino-4H-1,3-thiazines was studied. The rearrangement proceeds in acid media to form the intermediate 4-hydroxyhexahydropyrimidine-2-thiones and their tautomeric 3-oxoalkylthioureas and is accompanied by ring cleavages of the tetrahydropyrimidine-2-thiones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1690–1694, December, 1970.     

Reduction of 4-hydroxy(alkoxy)hexahydropyrimidine-2-thiones and 1,2,3,6-tetrahydropyrimidine-2-thiones by the NaBH4-CF3COOH system. Synthesis of hexahydropyrimidine-2-thiones

A convenient method for the synthesis of hexahydropyrimidine-2-thiones by the reduction of the readily accessible 4-hydroxy(alkoxy)hexahydropyrimidine-2-thiones and 1,2,3,6-tetrahydropyrimidine-2-thiones by the NaBH₄-CF₃COOH system was proposed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1378–1388, October, 1993.     

Additionsreaktionen von 2-Thiazolin-5-thionen mit Acetylenen Vorläufige Mitteilung

Addition Reactions of 2-Thiazolin-5-thiones with Acetylenes The reaction of the 2-thiazolin-5-thiones 1 and 5 , respectively, with acetylen carboxylates yields mainly 1, 4-dithiafulvenes of type 3. In the presence of the acetylenic compounds, the 1, 4-dithiafulvenes undergo an isomerization to give the corresponding 2, 3-dihydrothiophene-2-thiones 4.     

Conversion of 4- and 5-hydroxyaminothiazolidine-2-thiones under the action of alkalis

5-Hydroxyaminothiazolidine-2-thiones are oxidized in an alkaline medium to 5-hydroxyiminothiazolidine-2-thiones or undergo recyclization to derivatives of imidazolidine-2-thiones, depending on their structure. 4-Hydroxyaminothiazolidine-2-thiones break down under analogous conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1143–1145, August, 1989.     

Synthesis,structure, and reactivity of l,2,3,6-tetrahydropyrimidine-2-thiones

Dehydration of 4-hydroxyhexahydropyrimidine-2-thiones formed 1,2,3,6-tetrahydropyrimidine-2-thiones containing no substituent at the C₍₄₎ carbon atom. It is shown that the synthesized compounds, in contrast to their 4-alkyl-substituted analogs, react easily with various nucleophilic reactants (alcohols, butylmercaptan, benzenesulfinic acid, hydrazoic acid, p-toluidine) to form the corresponding 4-functionally substituted hexahydropyrimidine-2-thiones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1259–1270, September, 1993.     

1,4-Dithiafulvene aus der Umsetzung von 4,4-disubstituierten 1,3-Thiazol-5(4H)-thionen mit Acetylenderivaten

1,4-Dithiafulvenes, Products of the Reaction of 4,4-Disubstituted 1,3-Thiazol-5(4H)-thiones and Acetylenic Compounds On heating in toluene, 4,4-disubstituted 1,3-thiazol-5(4H)-thiones 1 and acetylenecarboxylates or acetylenecarbonitriles 2 undergo a cyclosubstitution reaction to yield 2-methylidene-1,3-dithiol derivatives 3 (1,4-dithiafulvenes) and a nitrile. Further heating of 3a and 3b in the presence of excess 2a leads to the isomeric 2,3-dihydrothiophene-2-thiones 4a and 4b , respectively. The benzodithiafulvene 14 has been formed in a similar reaction from 1a and in situ generate benzyne.     

Nucleophilic substitution at the C(4) atom in series of functionally 4-substituted hexahydropyrimidine-2-thiones. Synthesis of 4-alkylthiohexahydropyrimidine-2-thiones

Nucleophilic substitution at the C₍₄₎ atom in 4-hydroxy(alkoxy)hexahydropyrimidine-2-thiones under the influence of alkanethiols in acidic, neutral, and basic media, as a result of which 4-alkylthiohexahydropyrimidine-2-thiones are formed, was studied. Hydrolysis and alcoholysis of the latter lead to the corresponding 4-hydroxy- or 4-alkoxyhexahydropyrimidine-2-thiones. The three-dimensional structures of the 4-alkylthiopyrimidines obtained were established by PMR spectroscopy, and it was shown that the stereoisomers with an axially oriented alkylthio group are thermodynamically more stable.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 234–240, February, 1988.     

Synthesis of 4-(pyrazol-5-yl)-1,2,4-triazole-3-thiones

Condensation of pyrazolyl isothiocyanates 2 with N-substituted hydrazines provided the 2-methyl/phenyl-4-(pyrazol-5-yl)thiosemicarbazides 3 . Cyclization of 3 with formic acid-acetic anhydride or with triethyl orthoacetate-acetic anhydride provided 4-(pyrazol-5-yl)-l,2,4-triazole-3-thiones 4a-f and 5-methyl-4-(pyrazol-5-yl)-1,2,4-triazole-3-thiones 4g-I respectively.     

α-Thioureidoalkylation of 4-alkyl- and 4-phenylthiosemicarbazides

Previously unknown 1,3-dialkyl-4,5-bis[4-alkyl(phenyl)thiosemicarbazido]imidazolidine-2-thiones and 4,5,7-trialkylperhydroimidazo[4,5-e]-1,2,4-triazine-3,6-dithiones have been synthesized by the α-thio-ureidoalkylation of 4-alkyl(phenyl)thiosemicarbazides using 1,3-dialkyl-4,5-dihydroxyimidazolidine-2-thiones.     

Novel method for synthesis of 4-hydroxyhexahydropyrimidine-2-thiones

4-Hydroxyhexahydropyrimidine-2-thiones were obtained by reaction of N-(azidomethyl)- or N-(p-tlylsulfonylmethyl)thioureas with anions of 1,3-dicarbonyl compounds. The corresponding 1,2,3,6-tetrahydropyrimidine-2-thiones were synthesized by dehydration of the pyrimidines obtained.     

Photochemical synthesis of triazolo[3,4-b]-1,3(4H)-benzothiazines: a detailed mechanistic study on photocyclization/photodesulfurisation of triazole-3-thiones

Irradiation of 4-(2-halobenzyl)-5-substituted-1,2,4-triazole-3-thiones under base mediated (CH₃CN/2 M NaOH) condition afforded triazolo[3,4-b]-1,3(4H)-benzothiazines and desulfurized triazoles. Benzophenone sensitized photolysis of triazole-3-thiones gave desulfurized triazoles exclusively. The mechanism of the photocyclization/photodesulfurization and the involvement of singlet and triplet energy levels are discussed.     

Synthesis of 3-oxoisothiazolo[5,4-b] pyridines

3-Oxoisothiazolo[5,4-b]pyridines were synthesized for the first time by the reaction of 3-cyanopyridine-2-thiones or bis(3-cyanopyridyl) disulfides with concentrated sulfuric acid. It is demonstrated that 3-carbamoylpyridine-2-thiones are formed as intermediates. The 3-oxoisothiazolopyridines were converted to 3-bromoisothiazolopyridines and pyridine-2-thiones. The bromination of pyridine-2-thione was studied.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 508–512, April, 1982.     

Mineral supported syntheses of benzoxazine-2-thiones under microwave irradiation

An original montmorillonite K-10 clay catalysed cycloisomerisation of salicylaldehyde 4-arylthiosemicarbazones yields 3,4-dihydro-4-hydrazino-2H-benz[e]-1,3-oxazine-2-thiones, which on reductive dehydrazination on alumina-supported copper(II) sulfate readily furnish 3,4-dihydro-2H-benz[e]-1,3-oxazine-2-thiones under solvent-free microwave irradiation. Under the same conditions salicylaldehyde thiosemicarbazones undergo cyclodehydrazination to yield 2H-benz[e]-1,3-oxazine-2-thiones.     

Addition of Organolithium and Grignard Reagents to Pyrimidine-2(1H)-thione: Easy Access to 4-Substituted 3,4-Dihydropyrimidine-2(1H)-thiones

Organolithium and Grignard reagents are added to pyrimidine-2(1H)-thione, yielding 4-substituted 3,4-dihydropyrimidine-2-(1H)-thiones. Since the synthetic procedure can be performed on a multigram scale, and since pyrimidine-2(1H)-thione as well as the majority of organometallic reagents are readily available, the process described provides an easy access and complementary to other methods to 4-substituted 3,4-dihydropyrimidine-2-(1H)-thiones.     

One-pot synthesis of diverse 4-di(tri)fluoromethyl-3-cyanopyridine-2(1H)-thiones and their utilities in the cascade synthesis of annulated heterocycles

Diverse substituted 4-di(tri)fluoromethyl-3-cyanopyridine-2(1H)-thiones were synthesized via the Claisen condensation of alpha-methyl(methylene)ketones with di(tri)fluoroacetate, followed by the immediate Thorpe-Guareschi reaction of the preformed di(tri)fluoromethyl-1,3-diketones with cyanothioacetamide. The procedure allows facile synthesis of the di(tri)flouromethylated pyridine-2(1H)-thiones in 50-95% yields, without the need for isolation and purification of intermediates. Resultant 4-di(tri)fluoromethyl-3-cyanopyridine-2(1 H)-thiones were subsequently utilized in domino reactions to produce first various substituted thieno[2,3-b]pyridines and, then, thienopyridines polyannulated with pyridine, pyrimidine, benzodiazocine, diazepine, and pyran rings.