Rearrangements of the aminoalkylation products of tetrahydro-2H-1,3-oxazine-2-thione

The nature of the compounds afforded by the rearrangement of the aminopropylation and aminoethylation products of tetrahydro-2H-1,3-oxazine-2-thione (I) has been investigated. In both instances compounds that can be considered to result from ring opening at either the C-O or C-S bond of a hypothetical bicyclic intermediate of structure IV were obtained. The compounds required for identification of the rearrangement products have been prepared by the reaction of the 2-methylthio derivatives of 2-thiazoline, 5,6-dihydro-4H-1,3-thiazine, and 5,6-dihydro-4H-1,3-oxazine with the appropriate hydroxyalkylamine or mercaptoalkylamine.     

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.     

New organic nitrates. II. Synthesis of 2H-pyrido[2,3-e]-1,3-oxazine-2,4(3H)-diones, 2H-pyrido[4,3-e]-1,3-oxazine-2,4(3H)-diones, 2H-pyrido[4,3-e]-1,3-oxazin-4(3H)-ones, 2H-thieno[2,3-e]-1,3-oxazin-4(3H)-ones and 2H-thieno[3,4-e]-1,3-oxazin-2,4(3H)-diones

The preparation and the physico-chemical characterization of 2H-pyrido[2,3-e]-1,3-oxazine-2,4(3H)-diones, 2H-pyrido[4,3-e]-1,3-oxazine-2,4(3H)-diones, 2H-pyrido[4,3-e]-1,3-oxazin-4(3H)-ones, 2H-thieno[2,3-e]-1,3-oxazin-4(3H)-ones and 2H-thieno[3,4-e]-1,3-oxazine-2,4(3H)-diones are reported.     

Reduction of 4-fluoro-5-(1,1,2,2-tetrafluoroethyl)-3H-1,2-dithiole-3-thione with sodium sulfide: Synthesis of fluoro-containing sulfur-rich heterocycles

Treatment of 4-fluoro-5-(1,1,2,2-tetrafluoroethyl)-3H-1,2-dithiole-3-thione with 2 equivalents of sodium sulfide gives after acidification 3,4-difluoro-2-mercapto-1,6,6aλ⁴-trithiapentalene, which can be further reduced by sodium sulfide to 3,5-difluoro-4-mercapto-thiopyran-2-thione.     

Umsetzung von 3-(Dimethylamino)-2H-azirinen mit 1,3-Oxazolidin-2-thion zu 3-(2-Hydroxyethyl)-2-thiohydantoinen

Reaction of 3-(Dimethylamino)-2H-azirines with 1,3-Oxazolidine-2-thione to 3-(2-Hydroxyethyl)-2- thiohydantoins The reaction of 3-(dimethylamino)-2H-azirines 1 and 1,3-oxazolidine-2-thione ( 6 ), in MeCN at room temperature, yields, after hydrolytic workup, 3-(2-hydroxyethyl)-2-thiohydantoins 7 (Scheme 2). In the case of the spirocyclic 1c , crystallization of the crude reaction mixture leads to spiro [cyclopentane-1, 7′(7′aH)-imidazo [4, 3-b] oxazole] -5′-thione 8c . The mechanism is discussed.     

New tetrathiafulvalenes containing a 2,5-bis(thiophen-2-yl)pyrrole fragment: Synthesis, optical properties, and electrochemical behavior

The reaction of 1-(3-bromopropyl)-2,5-bis(thiophen-2-yl)-1H-pyrrole with cesium 5-methylsulfanyl-2-thioxo-1,3-dithiole-4-thiolate generated in situ gave previously unknown 4-{3-[2,5-bis(thiophen-2-yl)-1H-pyrrol-1-yl]propylsulfanyl}-5-methylsulfanyl-1,3-dithiole-2-thione, and cross-coupling of the latter with 4,5-disubstituted 1,3-dithiole-2-thiones in the presence of triethyl phosphite afforded new substituted tetrathiafulvalenes containing a 2,5-bis(thiophen-2-yl)pyrrole fragment. Optical properties and electrochemical behavior of the synthesized compounds were studied, and their ability to undergo electropolymerization was confirmed.     

Reaction of <Emphasis Type="Italic">N</Emphasis>-aryl-3-oxobutanethioamides with 2-amino-1,3-thiazole and 2-amino-1,3-benzothiazole

N-Aryl-3-oxobutanethioamides react with 2-amino-1,3-thiazole (2-amino-1,3-benzothiazole) in acetic acid to give mixtures of 7-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidine-5-thione (2-methyl-4H-pyrimido-[2,1-b][1,3]benzothiazole-4-thione) and 5-arylimino-7-methyl-5H-[1,3]thiazolo[3,2-a]pyrimidines (4-arylimino-2-methyl-4H-pyrimido[2,1-b][1,3]benzothiazoles), whose ratio depends on the nature of the aryl substituent in the initial butanethioamide.     

Condensation of 5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione with haloacetic acids

Reactions of triazolethiones with haloacetic acids were studied with 5-(4-methylphenyl)-2,4-dihydro-3H-1,2,4-triazole-3-thione as an example. It was proved for the first time by X-ray diffraction that the cyclocondensation of these compounds proceeds regiospecifically to give 2-(4-methylphenyl)[1,3]thiazolo[3,2-b][1,2,4]triazol-6(5H)-one rather than its isomer 3-(4-methylphenyl)[1,3]thiazolo[2,3-c][1,2,4]triazol-5(6H)-one.     

Synthesis and mass spectra of 4-mono- and 4,4-disubstituted 5,6-tetramethylenetetrahydro-1,3-oxazine-2-thiones

The syntheses and mass spectra of 5,6-tetramethylenetetrahydro-1,3-oxazine-2-thione and its 4-mono- and 4,4-disubstituted analogs are reported. The primary decay processes under electron impact are loss of the 1,3-oxazine ring, formation of hydrocarbon ions, and rearrangement of the [M–C₆H₉]⁺ ion.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1668–1672, December, 1989.     

Reaction of dialkyl 2-butynoate with aniline and formaldehyde: revision of the structure of the product

Dimethyl 3-(aryl)-3,6-dihydro-2H-1,3-oxazine-4,5-dicarboxylate structure assigned for the products obtained in the Bronsted acid catalyzed reaction of dimethyl but-2-ynoates with anilines and an excess of formaldehyde in methanol has been revised to methyl 1-(aryl)-3-(methoxymethyl)-4,5-dioxopyrrolidine-3-carboxylate.     

Stable carbenes. Synthesis and properties of benzimidazol-2-ylidenes

A new stable crystalline carbene, 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, was synthesized by decomposition of 1,3-bis(1-adamantyl)-2,3-dihydro-1H-benzimidazol-2-ylacetonitrile on heating under reduced pressure. Heteroaromatic 1,3-R₂-disubstituted benzimidazol-2-ylidenes, both stable (R = 1-Ad) and generated in situ (R = Me, Bzl), as well as 1,3,4,5-tetraphenylimidazol-2-ylidene (generated in situ), reacted with acetonitrile to give the corresponding insertion products, 1,3-disubstituted 2-cyanomethyl-2,3-dihidro-1H-(benz)-imidazoles. The geometric parameters of 1,3-bis(1-adamantyl)benzimidazol-2-ylidene, determined by X-ray analysis, suggest its lower aromaticity as compared to imidazol-2-ylidenes and 1,2,4-triazol-5-ylidenes. The structures of 2-cyanomethyl-2,3-dihydro-1H-benzimidazoles, 2-cyanomethyl-1,3,4,5-tetraphenyl-2,3-dihydro-1H-imidazole, and 1-(1-adamantyl)-5-cyanomethyl-3,4-diphenyl-4,5-dihydro-1H-1,2,4-triazole are characterized by partial conjugation in the heteroring; some compounds exhibit luminescence under UV irradiation. 1,3-Bis(1-adamantyl)benzimidazol-2-ylidene reacted with molecular sulfur in benzene to give 1,3-bis-(1-adamantyl)-2,3-dihydro-1H-benzimidazole-2-thione, but it failed to react with selenium under analogous conditions.     

Heterocyclization of functionalized heterocumulenes with C,N-, C,O-, and C,S-binucleophiles: VIII. Synthesis of pyrano(chromeno)[3,4-e][1,3]oxazines by condensation of 1-chloroalkyl isocyanates with 4-hydroxy-6-methylpyran-2-one and 4-hydroxycoumarin

1-Chlorobenzyl isocyanates react with 4-hydroxy-6-methylpyran-2-one and 4-hydroxycoumarin forming 4-aryl-3,4-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]oxazine-2,5-diones. The reaction of 1-aryl-2,2,2-trifluoro-1-chloroethyl isocyanates with the above substrates gives rise to structurally isomeric 2-aryl-2-trifluoromethyl-2,3-dihydro-2H,5H-pyrano(chromeno)[3,4-e][1,3]-oxazine-4,5-diones.     

Synthesis and reaction of polymers bearing 5-membered cyclic dithiocarbonate group

5-(Methacryloyloxy)methyl-1,3-oxathiolane-2-thione ( 3 ) was synthesized from glycidyl methacrylate (GMA) and carbon disulfide in the presence of lithium bromide in 93% yield. The radical polymerization of 3 in DMSO initiated by AIBN at 60°C afforded corresponding polymethacrylate 4 quantitatively. Copolymerization of 3 with MMA was also carried out. 5-Phenoxymethyl-1,3-oxathiolane-2-thione ( 6 ), model dithiocarbonate, reacts with benzylamine at room temperature to afford O-(1-mercapto-3-phenoxy-2-propyl)N-benzyl-thiocarbamate ( 7 ) and 1,1′-dithiobis[3-phenoxy-2-(benzylaminothiocarbonyloxy)-propane] ( 8 ) in 89% and 7% yield, respectively. Polymer 4 reacted with butylamine or dipropylamine to afford a corresponding polymethacrylate bearing thiol group, which immediately turned to insoluble gel by facile auto-oxidation of the thiol group. © 1995 John Wiley & Sons, Inc.     

Syntheses on the basis of 2H-chromen-2-one and 2H-chromene-2-thione

4-Hydroxy-2H-chromen-2-one and 4-hydroxy-2H-chromene-2-thione reacted with allyl bromide, 1,1,3-trichloroprop-1-ene, and 1,3-dichlorobut-2-ene to give the corresponding ethers, which were oxidized to (2-oxo-2H-chromen-4-yloxy)acetic acid with potassium permanganate, and various derivatives of that acid were obtained. 3-(3,3-Dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromen-2-one and 3-(3,3-dichloroprop-2-enyl)-7-hydroxy-4-methyl-2H-chromene-2-thione were synthesized, and some their transformations were studied.     

CHEMISTRY OF 1,3-OXAZINE-6-THIONES. RING TRANSFORMATION

Abstract

Two 1,3-oxazine-6-thione derivatives obtained by “S,N-Double Rearrangement²” reacted with several nucleophiles to produce 1,3-diazin-6-ones, 6-imino-1,3-oxazines, 1,3,4-triazoles, 1,2,4-oxadiazoles, and 1,3-thiazol-6-ones. Their ring transformations are discussed.     

Synthesis of 1H,3H-imidazo[1,5-c]thiazole-5,7-[6H,7aH]-dione and 7,8-dihydro-5-H-imidazo[1,5-c][1,3]thiazine-1,3-[2H,8aH]-dione and derivatives

1H,3H-Imidazo[1,5-c]thiazole-5,7-[6H,7aH]-dione and the corresponding 7-thione derivatives as well as 7,8-dihydro-5H-imidazo[1,5-c][1,3]thiazine-1,3-[2H,8aH]-dione and the corresponding 3-thione derivatives were synthesized starting from L -cysteine and DL -homocysteine thiolactone, respectively. The second group of bicyclic compounds represents a new heterocyclic ring system. The structures of the compounds were confirmed by spectroscopic studies and elemental analyses.     

Reaction of α,α-, α,α′-dihalothiones with 8-mercaptoquinolinium halides as a route to tetrahydro-1,4-thiazinoquinolinium halides

The reaction of 8-mercaptoquinolinium bromide with 1,3-dibromopropane-2-thione or 3,3-dibromobutane-2-thione in methanol gave the 2-bromomethyl-2-mercaptotetrahydro-1,4-thiazino[2,3,3,4-i,j]quinolinium and 3-bromo-2-mercapto-2,3-dimethyltetrahydro-1,4-thiazino[2,3,3,4-i,j]quinolinium bromides which readily exchanged the Br⁻ anion for ClO ₄ ⁻ upon treatment with sodium perchlorate in methanol. Oxidation of the 3-bromo-2-mercapto-2,3-dimethyltetrahydro-1,4-thiazino[2,3,3,4-i,j]-quinolinium bromide by selenium dioxide gave 2,2-dithiobis(3-bromo-2,3-dimethyltetrahydro-1,4-thiazino[2,3,3,4-i,j]quinolinium) bromide. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 11, pp. 1720–1723, November, 2006.     

[2+2+2] cycloaddition reactions of α,β-unsaturated N-arylaldimines,acetylenedicarboxylates and 2-arylidene-1,3-indanediones

The domino [2+2+2] cycloaddition reaction of α,β-unsaturated N-arylaldimines, dialkyl acetylenedicarboxylates and 2-arylidene-1,3-indanediones in dry methylene dichloride at room temperature afforded isomeric 2′-styryl-1,2′,3,4′-tetrahydro-1′H-spiro[indene-2,3′-pyridines] in good yields. Under similar conditions, the reaction of α,β-unsaturated N-arylaldimines with two molecules of dialkyl acetylenedicarboxylates resulted in 1-aryl-6-styryl-1,6-dihydropyridine-2,3,4,5-tetracarboxylates. Additionally, the three-component reaction of α,β-unsaturated N-arylaldimines, dimethylacetylenedicarboxylate and benzoyl cyanide also gave isomeric 1,3-oxazine-4,5-dicarboxylates.     

Reaktionen von 3-(Dimethylamino)-2H-azirinen mit 1,3-Benzoxazol-2(3H)-thion

Reaction of 3-(Dimethylamino)-2H-azirines with 1,3-Benzoxazole-2(3H)-thione The reaction of 3-(dimethylamino)-2H-azirines 2 with 1,3-benzoxazole-2(3H)-thione ( 5 ), which can be considered as NH-acidic heterocycle (pK_aca. 7.3), in MeCN at room temperature, leads to 3-(2-hydroxyphenyl)-2-thiohydantoins 6 and thiourea derivatives of type 7 (Scheme 2). A reaction mechanism for the formation of the products via the crucial zwitterionic intermediate A ′ is suggested. This intermediate was trapped by methylation with Mel and hydrolysis to give 9 (Scheme 4). Under normal reaction conditions, A ′ undergoes a ring opening to B which is hydrolyzed during workup to yield 6 or rearranges to give the thiourea 7. A reasonable intermediate of the latter transformation is the isothiocyanate E (Scheme 3) which also could be trapped by morpholine. In i-PrOH at 55–65° 2a and 5 react to yield a mixture of 6a , 2-(isopropylthio)-1,3-benzoxazole ( 12 ), and the thioamide 13 (Scheme 5). A mechanism for the surprising alkylation of 5 via the intermediate 2-amino-2-alkoxyaziridine F is proposed. Again via an aziridine, e.g. H ( Scheme 6 ), the formation of 13 can be explained.     

Zur Umsetzung des 3,4,5,6-Tetrahydro-6-hydroxy-4,4,6-trimethyl-1,3-thiazin-2-thions mit primären Aminen

Tetrahydro-6-hydroxy-4,4,6-trimethyl-1,3-thiazine-2-thione (1 a) reacts with methyl-, ethyl- and n-butylamine to the corresponding 1-alkyl-6-alkylaminotetrahydro-2(1H)-pyrimidinethione12 but withi-propylamine to tetrahydro-6-isopropylamino-1,3-thiazine-2-thione (6 d). On treatment withDCC,6 d is rearranged to dihydro-4-isopropylamino-2(1H)-pyridinethione (8 d), and 6-amino-tetrahydro-1,3-thiazinethione (6 a) to dihydro-4,4,6-trimethyl-2(1H)-pyrimidinethione (10 a). The reaction of 6-aminothiazinethiones6 a, d and 6-(4-morpholinyl)-thiazinethione13 resp., with methylamine leads to 1-methyl-6-methylamino-pyridinethione12 b. 1-Alkyl-6-alkylamino-tetrahydro-2(1H)-pyrimidinethiones (12) react at reflux temperature to dihydro-1-alkylpyrimidinethiones10. With methylamine only 6-methylamino-3,4,4,6-tetramethyl-1,3-thiazine-2-thione (6 f) is formed from tetrahydro-6-hydroxy-tetramethyl-1,3-thiazine-2-thione (1 b).