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.     

4- and 5-Hydroxylaminothiazolidine-2-thiones. Reaction with 4-nitrobenzaldehyde

Stable nitrones are formed in the condensation of 5-hydroxylaminothiazolidine-2-thiones with 4-nitrobenzaldehyde. At the same time, nitrones obtained from the isomeric 4-hydroxylaminothiazolidine-2-thiones, as well as 4-hydroxylaminoimidazolidin-2-one, can undergo rearrangement to E- or Z-O-substituted 4-nitrobenzaldoximes, depending on the structure and the reaction conditions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 544–548, April, 1991.     

Synthesis of new 1,2,4-triazolines and 1,3,4-thiadiazolines from bithioureas

2,4-Disubstituted thiosemicarbazides 1 react with acyl isothiocyanates to give bithioureas 2 , which by the action of sodium ethanolate cyclize to 1,2,4-triazoline-3-thiones 3 and 5 , respectively. Treatment of 2 with methyl iodide yields 1,3,4-thiadiazoline-2-imines 8 isomeric with 3 . Compound 8d undergoes a thermal induced DIMROTH rearrangement to give 3d in good yield.     

The rearrangement of 3,4-disubstitued-Δ2-1,2,4-oxadiazolin-5-thiones

The light and metal catalysed rearrangement of 3,4-disubstituted-Δ²-1,2,4-oxadiazolin-5-thiones (3) to the corresponding Δ²-1,2,4-thiodiazolin-5-ones (4) is described. The thermal stability of (3) is in great great contrast to the ease of rearrangement of the acyclic analogues. The rearrangement of (3) and (4) under electron impact are described.     

Synthesis of thienothiopyranthiones by a new molecular rearrangement

On heating with alkynes, the readily prepared 1,3-dithioles 3 undergo a new cycloaddition reaction and an unprecedented molecular rearrangement with loss of chlorine to give the first 7H-thieno[2,3-c]thiopyran-7-thiones 4 and 4H-thieno[3,2-c]thiopyran-4-thiones 5 whose structures were confirmed by X-ray diffraction. Unexpectedly, the different alkynes used to form 3 and to convert it into 4 and 5 were incorporated regiospecifically into the thiophene and thiopyran rings, respectively. [reaction: see text]     

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.     

The intramolecular rearrangement of substituted 4-hydroxyhexahydropyrimidine-2-thiones

It has been found that, on being heated with 36% hydrochloric or 85% orthophosphoric acid, substituted 4-hydroxyhexahydropyrimidine-2-thiones (IA) undergo an intramolecular rearrangement connected with the transformation of the cyclic forms IA into the linear tautomers IB and accompanied by dehydration with the formation of substituted 2-alkylamino- or 2-arylamino-4H-1, 3-thiazines.     

COPPER-CATALYSED REARRANGEMENT OF 4-SUBSTITUTED-2,3-1H-BENZOXAZINE-1-THIONES

Abstract

4-Substituted-2,3-1H-benzoxazine-1-thiones were prepared by the treatment of the corresponding benzoxazine-1-ones with P₂S₅. The thermal rearrangement of 4-substituted-2.3-1H-benzoxazine-1-thiones, catalysed by metallic copper, yielded 4-substituted-2.3-1 H-benzthiazine-1-ones.     

The preparation and some reactions of 1,3,2-thiazaphospholidine-2-ones

1,3,2-Thiazaphospholidine-2-ones have been prepared by rearrangement of the corresponding 1,3,2-oxazaphospholidine-2-thiones. The stereochemical course of ring opening reactions has been investigated.     

Synthesis of substituted 2-arylimino-2,3-dihydro-4H-1,3-thiazines

The synthesis of 3,4,4,6-tetramethyl-2-arylimino-2,3-dihydro-4H-1,3-thiazines, which have a fixed imino structure, was accomplished by two methods: by intramolecular rearrangement of 1,4,6,6-tetramethyl-3-aryl-1,2,3,6-tetrahydropyrimidine-2-thiones and by amination of 3,4,4,6-tetramethyl-2,3-dihydro-4H-1,3-thiazine-2-thione methiodide.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 941–943, July, 1972.     

Synthesis and regioselectivity of the [3,3]-sigmatropic rearrangement of substituted 2-allylthio- and 2-allylseleno-1,4-dihydropyridines

The reaction of 3-cyano-1,4-dihydropyridine-2-thiolates and the corresponding selenolates with allyl bromide gave 2-allylthio- and 2-allylseleno-3-cyano-1,4-dihydropyridines, which, upon heating in various solvents or in the solid state, undergo [3,3]-sigmatropic rearrangement to give 3-cyano-3-allyl-1,2,3,4-tetrahydropyridine-2-thiones and the corresponding selenones. The resultant pyridinethiones are alkylated by alkyl halides at the sulfur atom and are oxidized by iodine to give disulfides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1888–1895, August, 1991.     

Mechanistic insights into the chemistry of RuII complexes containing Cl and DMSO ligands

Two new isomers trans,mer-[RuIICl2(bpea)(DMSO)], 2a, and cis,fac-[RuIICl2(bpea)(DMSO)], 2b, (bpea = N,N-bis(2-pyridylmethyl)ethylamine), as well as the bis-DMSO complex trans,fac-[RuIICl(bpea)(DMSO)2]Cl, 3, have been synthesized and characterized by cyclic voltammetry and UV-vis and 1D and 2D NMR spectroscopy in solution. Their solid-state structure has also been solved by means of single-crystal X-ray diffraction analysis. All the three complexes display a ruthenium metal center possessing a distorted-octahedral type of coordination, where the bpea ligand is coordinated in a meridional fashion in 2a and in a facial fashion in 2b and 3. The isomer 2a is the kinetically favored and thus can be thermally converted into 2b, that is the thermodynamically favored one. A thorough kinetic analysis strongly points toward a dissociative mechanism, where in the first step a chloro ligand is removed from the metal coordination sphere, followed by a geometric rearrangement before the chloro ligand coordinates again, generating the final complex. DFT calculations agree with the experimental data for the proposed mechanism and allow us to further characterize the mechanism of the 2a --> 2b rearrangement by obtaining the intermediates and transition state.     

Electron ionization mass spectra of 3,4-disubstituted-1,2,4-oxa(thia)diazole-5(4H)-thione(ones). Substituent effects on the mass spectrometric rearrangement of 3-aryl-4-(p-tolyl)-1,2,4-oxadiazole-5(4H)-thiones to the corresponding oxo compounds

The fragmentation behaviour of ten 3,4-disubstituted 1,2,4-oxadiazole-5(4H)-thiones and seven 3,4-disubstituted 1,2,4-thiadiazole-5(4H)-ones studied here confirmed the earlier observations about the partial rearrangement of the former after ionization into the latter before further fragmentation. In the case of eight 3-(substituted phenyl)-4-(p-tolyl)-1,2,4-oxadiazole-5(4H)-thiones the fragmentations reflecting the above-mentioned molecular ion rearrangement show a clear correlation on the substituent sigma values. The electron-withdrawing substituents destabilize the molecular ion, so higher amounts of the rearranged ion [R(1)NCO](+.) are obtained. A good correlation of log[R(1)NCO](+) against sigma was obtained (r = 0.96). Only a satisfactory correlation prevailed for log([R(1)NCO](+)*/[R(1)NCS](+)*) against sigma(r = 0.87).     

Reactions involving the formation and recyclization of heterocycles

The reaction of 5-aryl-1,3,4-oxadiazole-2-thiones with hydrazine and hydrazides proceeds with recyclization of the oxadiazole ring to a triazole ring. Depending on the nature of the aryl residue, adducts of 5-aryl-1,3,4-oxadiazole-2-thiones with hydrazine can be isolated in a number of cases. 6-Aryl-2-methyldihydro-1,2,4,5-tetrazine-3-thiones are formed with methylhydrazine as a result of recyclization.See [1] for communication VIII.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 905–909, July, 1971.     

4-thiazohne-2-thiones. III. The thermodynamic stability of intermediate,tautomeric thiazolidines and dithiocarbamates

The intermediate products isolated from preparations of 3-substituted 4-thiazoline-2-thiones by the reaction of primary amines, carbon disulfide, and α-haloketones may be either 4-hydroxy-thiazolidine-2-thiones or dithiocarbamates. Tautomeric equilibrium of the two types of intermediates in solution is demonstrated, and the more thermodynamically stable form is determined. Steric and electronic effects of substitution on stability are described.     

Cd-Based Metal–Organic Framework for Selective Turn-On Fluorescent DMSO Residual Sensing

Dimethyl sulfoxide (DMSO) is a universally used solvent in various synthetic reactions, and trace amounts of DMSO residual are often seen on the surface of chemical product. It is difficult to quickly determine whether the residual DMSO is washed completely. This work reports a Cd^II metal–organic framework (MOF) SXU-4 which can detect trace amounts of DMSO in various solvents. Fluorescence experiments reveal its turn-on fluorescence effect toward DMSO with high selectivity and sensitivity, indicating that it can be used as an effective luminescent probe for rapid chemical product purity detection by testing the washing solution. Crystallographically characterized DMSO loaded SXU-4 (DMSO@ SXU-4 ), in combination with computational results uncover that the enhanced DMSO–MOF conjugation through multiple DMSO–MOF supramolecule interactions and charge rearrangement are the main causes of fluorescence intensification.     

Synthesis of 3-amino-4-hydroxylaminothiazolidine-2-thiones and 2,3-dimethyl-4a,5-dihydro-7-thioxothiazolo[3,4-b]-1,2,4-triazines

The reaction of dimeric nitroso chlorides of olefins with potassium dithiocarbazate was used to synthesize 3-amino-4-hydroxylaminothiazolidine-2-thiones, which undergo rearrangement to 2-mercapto-1,3,4-thiadiazines on heating and react with butane-2,3-dione to give 2,3-dimethyl-4a,5-dihydro-7-thioxothiazolo[3,4-b]-1,2,4-triazine 4-oxides. The latter are reduced by sodium borohydride to the corresponding 3,4,4a,5-tetrahydro-7-thioxo derivatives.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 554–556, April, 1987.     

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.     

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.     

Une nouvelle reaction de transposition: acces facile a des thiopyranne thiones a partir de (dimethylamino-2 vinyl)-5 alkylthio-3 dithiole-1,2 yliums

Reduction by potassium borohydride of 5-(2-dimethylaminovinyl) 3-alkylthio 1,2-dithiole yliums yields, 4-alkylthio 2H-thiopyranne 2-thiones, or 2-alkylthio 4H-thiopyranne 4-thiones (depending on the alkyl group); these react with secondary amines to yield 4-amino 2H-thiopyranne 2-thiones.