Pyridinethiones. VIII. The aldol and wittig condensations of 3-formyl-2(1H)-pyridones, -thiones and -selones. Preparation of new cyanopyridones

Condensations of 1-substituted-3-formyl-2(1H)-pyridones, -thiones and -selones with methyl ketones such as acetophenone give the corresponding chalcones in high yields. Geometry at the vinyl hydrogens is E. These chalcones can be cyclized with ethyl cyanoacetate in the presence of ammonium acetate to form new 3-cyano-2(1H)-pyridones. An effective “one-pot” preparation is worked out and an intermediate from the cyclization reaction is isolated. Via the Wittig reaction it is possible to prepare condensation products from 1-substituted-3-formyl-2(1H)-pyridinethiones and -selones with mainly Z geometry at the vinyl hydrogens.     

Bildung tricyclischer Thietan-Derivate durch intramolekulare(2+2)-Cycloaddition

Formation of Thietane Derivatives via Intramolecular (2+2) Cycloaddition On irradiation, the two 4-vinyl-1,3-thiazole-5(4H)-thiones 1a, b , synthesized from thiobenzoic acid and the corresponding 3-amino-2H-azirines 2a , b , undergo an intramolecular (2+2)-cycloaddition reaction of the C?S and C?C bonds to give the tricyclic thietane derivatives 3a , b .     

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.     

Polyazasteroids II.. 1,2,4-Triazolol[3′,4′:2,3]pyrimido[4,5-c]quinolin- 11(12H)ones,imidazo[2′,1′:2,3]pyrimido[4,5-c]quinolin-11(12H)ones and 2,3-dihydroimidazo[2′,1′:2,3] pyrimido[4,5-c]quinolin-11(12H)ones

Starting with 2-substituted quinoline-3,4-dicarboxylic acids, a series of substituted 1,2,3,4-tetrahydropyrimido[4,5-c]quinolinone-3-thiones were obtained. The latter compounds were converted to the three novel polyazasteroid series: 1,2,4-Triazolo[3′,4′:2,3]pyrimido[4,5-c]-quinolin-11(12H)ones, imidazo[2′,1′:2,3]pyrimido[4,5c]quinolin-11(12H)ones and 2,3-dihydroimidazo[2′,1′:2,3]pyrimido[4,5-c]quinolin-11(12H)ones. The intermediate 3-hydrazino-1,2-dihydropyrimido[4,5-c]quinolinones and nitrous acid gave the 3-azido derivatives rather than the tetrazolo compounds.     

Reaktion von Phenyldiazomethan mit 1,3-Thiazol-5(4H)-thionen: Basenkatalysierte Ring-Öffnung des Primäradduktes

Reaction of Phenyldiazomethane with 1,3-Thiazole-5(4H)-thiones: Base-Catalyzed Ring Opening of the Primary Adduct Reaction of 1,3-thiazole-5(4H)-thiones 1 and phenyldiazomethane ( 2a ) in toluene at room temperature yields the thiiranes trans- and cis-1,4-dithia-6-azaspiro[2.4]hept-5-enes (trans- and cis- 4 ; Scheme 2). With Ph₃P in THF at 70°, these thiiranes are transformed stereospecifically into (E)- and (Z)-5-benzylidene-4,5-dihydro-1,3-thiazoles 5 , respectively. In the presence of DBU, 1 and 2a react to give 1,3,4-thiadiazole derivatives 6 or 7 via base-catalyzed ring opening of the primary cycloadduct (Scheme 3). In the case of 2-(alkylthio)-substituted 1,3-thiazole-5(4H)-thiones 1c and 1d , this ring opening proceeds by elimination of the corresponding alkylthiolate, yielding isothiocyanate 7 . The structures of (Z)- 5c and 6b have been established by X-ray crystallography.     

Pyridinethiones. VI. The synthesis of 2H-Thiopyrano[2,3-b]pyridin-2-ones

A general and versatile method for the preparation of 2H-thiopyrano[2,3-b]pyridin-2-ones is described. The starting materials, the β, β-disubstituted vinyl-1-t-butyl-2-(1H)pyridinethiones were prepared from the synthon 3-formyl-1-t-butyl-2-(1H)pyridinethione by condensation. ¹³H nmr spectra showed the vinyl double bond of the condensation products to have the trans configuration with the smallest group close to the sulfur atom. Some reactions of these new azaanalogues of thiocoumarins are reported.     

1,2,5-Selenadiazoles. Synthesis and properties

4-Amino-1, 2, 5-selenadiazole-3-carboxylic acid and 4-amino-1, 2, 5-selenadiazole-3-carboxamides have been prepared by ring-cleavage of [1, 2, 5]selenadiazolo[3, 4-d]pyrimidin-7(6H)-one by basic reagents. The primary amide (III), as well as an N-alkyl amide, may be produced by the action of a primary amine. Hydrazine reductively cleaves the selenadiazole ring. The preparation of similar 4-ureido derivatives by ring-cleavage of [1,2,5]selenadiazolo[3, 4-d]pyrimidine-5, 7(4 H, 6H)-dione has been demonstrated with two examples. N-Butyl-4-ureido-1, 2, 5-selenadiazole-3-carboxamide is easily hydrolyzed in aqueous base to the corresponding acid, and it has been shown that this reaction proceeds by way of [1, 2, 5]selenadiazolo[3,4-d]pyrimidine-5, 7 (4H, 6H)-dione. The 4-amino-1, 2, 5-selenadiazole-3-carboxylic acid derivatives have marked cytotoxic, antibacterial, and antifungal activity.     

N-(1,3-Thiazol-5(4H)-yliden)amine aus 1,3-dipolaren Cycloadditionen von Aziden mit 1,3-Thiazol-5(4H)-thionen

N-(1,3-Thiazol-5(4H)-ylidene)amines via 1,3-Dipolar Cycloaddition of Azides and 1,3-Thiazol-5(4H)-thiones Organic azides 5 and 4,4-dimethyl-2-phenyl-1,3-thiazol-5(4H)-thione ( 2 ) in toluene at 90° react to give the corresponding N-(1,3-thiazol-5(4H)-ylidene)amines (= 1,3-thiazol-5(4H)-imines) 6 in good yield (Table). A reaction mechanism for the formation of these scarcely investigated thiazole derivatives is formulated in Scheme 3: 1,3-Dipolar azide cycloaddition onto the C?S group of 2 leads to the 1:1 adduct C . Successive elimination of N₂ and S yields 6 , probably via an intermediate thiaziridine E .     

Zur Synthese der 4-Dialkylamino-5,6-dihydro-2(1H)-pyridinthione sowie entsprechender 4-Alkylamino- bzw. 4-Arylaminoverbindungen

The rearrangement of 1-alkyl- and 1-aryldihydro-6-methyl-2(1H)-pyrimidinethiones (1 a) or-ones (1 b) and of methylene compounds (2a, 2b) resp., to 4-alkylamino- and 4-arylaminodihydro-2(1H)-pyridinethiones (4 a) or-ones (4 b) takes place via the corresponding 3-alkylamino- and 3-aryl-amino-3-butenylisothiocyanates (3 a) or-isocyanates (3 b). Dialkylamino-dihydro-2(1H)-pyridinethiones (10) are formed by heating dihydro-6-methyl-2(1H)-pyrimidinethiones (6 a) and 3,4-dihydro-6-methyl-1,3-thiazin-2-thiones (6 b) with dialkylformamides and by the reaction of secondary amines with tetrahydro-6-hydroxy-6-methyl-1,3-thiazin-2-thiones (5 a), with N,N-dialkyl-N-(3-oxobutyl)-thioureas (7) and 3-oxobutyl isothiocyanates (8). A general method for the preparation of10 is the reaction of dialkylammoniumrhodanides12, N,N-dialkylthioureas13 and dialkylammonium chlorides and KCNS, resp., with 3-alken-2-ones14 and 4-hydroxy-2-alkanones15, resp. Methyl ketones such as acetone, which readily undergo the aldol condensation, behave analogously. The reactions described take place via the intermediate aminoalkenyl isothiocyanates (9).     

Synthesis of indeno[2,1-b][1,4]benzothiazine derivatives from 2-bromoinden-1-ones

2-Bromoinden-1-ones 2 were condensed with 6-substituted 3-aminopyridine-2(1H)-thiones to produce a new type of 4-azaindeno[2,1-b][1,4]benzothiazine derivatives 3 . Substituted 6-phenylindeno[2,1-b][1,4]benzothiazines 4 were also prepared by reacting 2-bromo-5-methoxy- and 2,6-dibromo-5-methoxyinden-1-ones with o-aminobenzenethiol.     

Facile Synthesis of 6-Aryl-3-cyanopyridine-2-(1H)-thiones from Aryl Ketones

An improved synthesis of 6-aryl-3-cyanopyridine-2-(1H)-thiones utilizing enaminones as starting materials catalyzed by 1,4-diazabicyclo[2.2.2]octane (DABCO) was described. Moreover, a convenient one-pot conversion of aryl ketones to 6-aryl-3-cyanopyridine-2-(1H)-thiones was also developed in moderate to good yields (up to 80%).     

Regioselective synthesis and properties of 3-cyano-6-thienylpyridine-2(1H)-thiones

Reactions of sodium derivatives of 2- and 3-thenoylacetaldehydes with cyanothioacetamide gave 2- and 3-cyano-6-thienylpyridine-2(1H)-thiones, which were used in the synthesis of substituted 2-alkylthiopyridines, thieno[2,3-b]pyridines, and other fused heterocycles. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 365–368, February, 1998.     

Asymmetric induction in the reactions of azinones with C-nucleophiles

Effect of acylating agents on the course of addition of C-nucleophiles to 1,2,4- and 1,3,5-triazinones, as well as to quinoxalin-2(1H)-one, was studied. A series of new azinone derivatives was obtained. A method for the preparation of diastereomerically pure addition products of indoles to 1,2,4-triazinones and quinoxalin-2(1H)-one in the presence of N-Ts-L-amino acid acyl chlorides was suggested.     

Synthesis of the alkaloid thalactamine and a new synthesis for the alkaloid N-methyl-6,7-dimethoxy-1(2H)isoquinolone

The alkaloid thalactamine (N-methyl-5,6,7-trimethoxy-1(2H)isoquinolone) was synthesised in two steps from 4,5,6-trimethoxyhomophthalic acid (1a). Heating la with DMF/POCI₃ at 100° furnished thalactamine-4-earhoxylic acid which was easily decarboxylated to give the alkaloid thalactamine. By the same two steps, the alkaloid N-methyl-6,7-dimethoxy-1(2H)-isoquinolone is obtained from 4,5-dimethoxyhomophthalic acid. Synthesis for la from 2-bromogallic acid trimethyl ether was modified to give excellent yield. 5,6,7-Trimethoxy and 6,7-dimethoxyisocoumarin-4-carboxylic acid esters were synthesised from the homophthalic acids 1a and b by interacting them with DMF/phosphoryl chloride at 0°, to give corresponding 4-(N,N-dimethylaminoformylidene)isochroman-1,3-dione derivatives Vla and b and treating their alcoholic solutions with dry hydrogen chloride gas. The isocoumarins were converted into N-methyl-1(2H)isoquinolonesby treating them with aqueous methylamine. The isochromandione Vla slowly changed into 3-chloro-4-formyl-5,6,7-trimethoxyisocoumarin during the working up of the reaction.     

Synthesis and transformations of 3-acetylpyridine-2(1<Emphasis Type="Italic">H</Emphasis>)-thiones

Reactions of substituted 3-cyanopyridine-2(1H)-thiones with methyllithium gave 3-acetylpyridine-2(1H)-thiones. The best results were achieved by adding a solid-state thione to a solution of methyllithium in ether (thione: MeLi = 1: 3). The compounds obtained and their 3-pentanoyl analogs were used to synthesize a number of fused heterocyclic systems. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1504–1507, July, 2008.     

Photocycloaddition of Quinoxaline-2(1H)-thiones to Alkenes

A synthetically useful C? C bond formation involving the photochemical addition of quinoxaline-2(1H)-thiones to alkenes is described. Irradiation of the quinoxaline-2(1H)-thiones 1–4 in the presence of the alkenes 7 gave the 2-(2′-mercaptoalkyl)quinoxalines 8–11 in moderate-to-good yields via ring cleavage of an intermediate aminothietane with aromatization of the quinoxaline ring. The latter was formed by [2+2] photocycloaddition of the C?S bond of the quinoxaline-2(1H)-thione and the C?C bond of the alkene.     

Efficiency of alkoxyl radical product formation from 5-substituted 3-alkoxy-4-methylthiazole-2(3H)-thiones

In a comparative study, reactions between 5-(p-methoxyphenyl)-substituted 3-alkoxy-4-methylthiazole-2(3H)-thiones and appropriate mediators (BrCCl₃, Bu₃SnH) provided higher yields of alkoxyl radical products (δ-bromohydrins, cyclic ethers, carbonyl compounds) than respective transformations of 5-phenyl- and 5-methyl-substituted derivatives. The unusual selectivity of applied thiohydroxamates to furnish products of O-alkylation, even upon treatment with soft carbon electrophiles, and the marked propensity of 3-alkoxy-5-(p-methoxyphenyl)-4-methylthiazole-2(3H)-thiones to crystallize, facilitated preparation and purification of the new family of alkoxyl radical precursors in a noteworthy manner.     

Acetylenic ketones. Part V. Reaction of acetylenic ketones with thiourea and some of its derivatives

Aroylphenylacetylenes (I) reacted with thiourea and S-benzylisothiourea to give 4,6-diaryl-pyrimidine-2(1H)thiones (IV) and α-aroyl-β-benzylmercaptostyrenes (X), respectively. Methyla-tion and acetylation of the thiones (IV) gave the corresponding S-methyl- (V) and S-acetyl- (VI) derivatives, respectively. The oxidation of these thiones gave the corresponding disulfide derivatives (VII). Reaction of α-aroyl-β-benzylmercaptostyrenes (X) with hydrazine hydrate and phenylhydrazine gave 3(5)-aryl-5(3)-phenylpyrazoles (XI) and 3-aryl-1,5-diphenylpyrazoles (XIII), respectively. Reaction of aroylphenylacetylenes (1) with N-allylthiourea gave 1-allyl-4,6-diaryl-pyrimidine-2-thiones (XVI).     

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.     

Carbophile Additionen von Organocupraten mit 1,3-Thiazol-5(4H)-thionen

Carbophilic Additions of Organocuprates and 1,3-Thiazole-5(4H)-thiones Organocuprates and 1,3-thiazole-5(4H)-thiones 1 react in THF at 0° via carbophilic addition onto the C? S bond to give 4,5-dihydro-1,3-thiazole-5-thiols 3 (Scheme 3). This observation is in marked contrast to the previously described reaction of organolithium compounds and 1 , which undergo a thiophilic addition onto the exocyclic S-atom. As an exception, treatment of the 1,3-thiazole-5(4H)-thione 1a with tert-butyl cuprate leads to 7a (Scheme 3).