Reactions of 1,3-Dialkyl-5-amino-1,3-dihydro-2<Emphasis Type="Italic">H</Emphasis>-imidazo-[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridin-2-ones with acetylacetone and ethyl acetoacetate

1,3-Dialkyl-5-amino-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones reacted with acetylacetone to give the corresponding 4-(1,3-dialkyl-2-oxo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-5-ylamino)pent-3-en-2-ones which underwent intramolecular cyclization to 1,3-dialkyl-5,7-dimethyl-1,3-dihydro-2H-imidazo[4,5-b]-[1,8]naphthyridin-2-ones on heating in polyphosphoric acid or diphenyl ether. Analogous reaction of 1,3-dialkyl-5-amino-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones with ethyl acetoacetate led to the formation of ethyl 3-(1,3-dialkyl-2-oxo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-5-ylamino)but-2-enoates whose cyclization afforded 1,3-dialkyl-8-hydroxy-7-methyl-1,3-dihydro-2H-imidazo[5,4-b][1,8]naphthyridin-2-ones.     

Iodocyclization of 2-[allyl(methallyl)sulfanyl]-6-(trifluoromethyl)pyrimidin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

Iodination of 2-[allyl(methallyl)sulfanyl]-6-(trifluoromethyl)pyrimidin-4(3H)-ones was accompanied by cyclization to 2,3-dihydro[1,3]thiazolo[3,2-a]pyrimidin-4-ium triiodides. 3-(Iodomethyl)-3-methyl- 7-oxo-5-(trifluoromethyl)-2,3-dihydro[1,3]thiazolo[3,2-a]pyrimidin-4-ium triiodide was reduced with sodium iodide to 3,3-dimethyl-7-oxo-5-(trifluoromethyl)-2,3-dihydro[1,3]thiazolo[3,2-a]pyrimidin-4-ium iodide.     

Reactions of 2-(2-propynylsulfanyl)-5,6,7,8-tetrahydrobenzo[<Emphasis Type="Italic">b</Emphasis>]thieno[2,3-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(<Emphasis Type="Italic">3H</Emphasis>)-one with arylsulfenyl chlorides

2-(2-propynylsulfanyl)-5,6,7,8-tetrahydrobenzo[b]thieno[2,3-d]pyrimidin-4(3H)-one with arylsulfenyl chlorides in chloroform gave products of anti-Markownikoff Ad _E-addition. The use of nitromethane as solvent in the presence of lithium perchlorate additives favored intramolecular electrophilic cyclization into 1-arylsulfanyl-1,2,6,7,8,9-hexahydro-4H-benzo[4,5]thieno[3,2-e][1,3]thiazolo[3,2-a]-pyrimidin-5-one.     

Synthesis and Structure of 4-Indolyl-5-(thieno[3,2-<Emphasis Type="Italic">b</Emphasis>]pyrrol-6-yl)imidazoles

A procedure was proposed for regioselective acylation of methyl 2-methyl-4H-thieno[3,2-b]-pyrrole-5-carboxylate with 2-(3-indolyl)-2-oxoacetyl chloride. Reactions of the resulting methyl 6-[2-(3-indolyl)-1,2-dioxoethyl]-2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylate with aromatic aldehydes and ammonium acetate in acetic acid afforded the corresponding methyl 6-[2-aryl-4-(3-indolyl)imidazol-5-yl]-2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylates. The structure of methyl 6-[2-(4-chlorophenyl)-4-(3-indolyl)imidazol-5-yl]-2-methyl-4H-thieno[3,2-b]pyrrole-5-carboxylate was studied by X-ray analysis.     

Fused pyrimidine systems: XVI. Electrophilic intramolecular cyclization of 2-(alkenylsulfanyl)pteridin-4(3<Emphasis Type="Italic">H</Emphasis>)-ones

2-[Allyl(but-3-en-1-yl, pent-4-en-1-yl)sulfanyl]pteridin-4(3Н)-ones at heating in polyphosphoric acid undergo an intramolecular cyclization affording respectively 9-methyl-8,9-dihydro-5H-[1,3]thiazolo[3,2-a] pteridin-5-one and 10-methyl(ethyl)-9,10-dihydro-5Н,8Н-[1,3]thiazino[3,2-a]pteridin-5-ones of angular structure. The cyclization of 2-(alkenylsulfanyl)pteridin-4(3Н)-ones under the action of iodine or arylsulfenyl chlorides afforded iodo(arylsulfanyl) derivatives of angularly fuzed thiazolo- and thiazinopteridines.     

Synthesis of 1-(1,3-dialkyl-2-oxo-2,3-dihydro-1<Emphasis Type="Italic">H</Emphasis>-imidazo-[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridin-5-yl)-5-oxopyrrolidine-3-carboxylic acids

Nitration of 2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-one gave its 5-nitro derivative which was subjected to alkylation with dimethyl sulfate, diethyl sulfate, and benzyl(dimethyl)phenylammonium chloride. The resulting 1,3-dimethyl-, 1,3-diethyl-, and 1,3-dibenzyl-5-nitro-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones were reduced to the corresponding 1,3-dialkyl-5-amino-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones, and the latter reacted with itaconic acid to produce 1-(1,3-dialkyl-2-oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-5-yl)-5-oxopyrrolidine-3-carboxylic acids. 1-(2-Oxo-2,3-dihydro-1H-imidazo[4,5-b]pyridin-5-yl)-5-oxopyrrolidine-3-carboxylic acid was obtained by analogous reaction with 5-amino-2,3-dihydro-1H-imidazo[4,5-b]-pyridin-2-one.     

Electrophilic heterocyclization of 6-alken(yn)ylsulfanyl-pyrazolo[3,4-<Emphasis Type="Italic">d</Emphasis>]pyrimidin-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

6-Allylsulfanyl-1-arylpyrazolo[3,4-d]pyrimidin-4(5H)-ones react with iodine and sulfuric acid to give angular pyrazolothiazolopyrimidine derivatives. The reaction of 6-(prop-2-yn-1-ylsulfanyl)-1-(4-tolyl)-pyrazolo[3,4-d]pyrimidin-4(5H)-one with sulfuric acid gives angularly fused pyrazolo[4,3-e][1,3]thiazolo-[3,2-a]pyrimidin-4-one, whereas in the reaction with sodium methoxide linearly fused pyrazolo[3,4-d][1,3]-thiazolo[3,2-a]pyrimidin-4-one was formed. Linearly fused pyrazolo[3′,4′:4,5]pyrimido[2,1-b][1,3]thiazole derivatives were also obtained by reaction of 1-aryl-6-(3-phenylprop-2-en-1-ylsulfanyl)pyrazolo[3,4-d]pyrimidin-4(5H)-ones with sulfuric acid.     

Halocyclization of 3-{[2-methyl(bromo)prop-2-en-1-yl]-sulfanyl}-5<Emphasis Type="Italic">H</Emphasis>-[1,2,4]triazino[5,6-<Emphasis Type="Italic">b</Emphasis>]indoles

Reactions of 3-[(2-bromoprop-2-en-1-yl)sulfanyl]-5H-[1,2,4]triazino[5,6-b]indole with bromine and of 3-[(2-methylprop-2-en-1-yl)sulfanyl]-5H-[1,2,4]triazino[5,6-b]indole with iodine and bromine afforded 3-halomethyl-10H-[1,3]thiazolo[3′,2′: 2,3][1,2,4]triazino[5,6-b]indol-4-ium halides whose structures were determined by ¹H NMR and X-ray analysis.     

Nitration of 1,3-dihydro-2<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridin-2-one derivatives

Nitration of 1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one and its N-methyl derivatives at 0–5°C and 60°C gives 5-nitro-and 5,6-dinitro-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones, respectively. The latter can also be obtained by nitration of 5-mononitro derivatives under similar conditions. The nitration of 6-chloro-and 6-bromo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones and their N-methyl-substituted analogs leads to the formation of the corresponding 6-chloro(bromo)-5-nitro compounds. The same products are formed in the nitration of 5,6-dichloro-and 5,6-dibromo-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones. In this case, the process involves replacement of the halogen atom in position 5 of the pyridine fragment by nitro group. The nitration of 6-bromo-5-methyl-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-one is accompanied by oxidation of the 5-methyl group to carboxy.     

Five-membered 2,3-dioxo heterocycles: LI. Reaction of 3-aroyl-2,4-dihydro-1<Emphasis Type="Italic">H</Emphasis>-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones with 3-amino-5,5-dimethylcyclohex-2-en-1-ones

3-Aroyl-2,4-dihydro-1H-pyrrolo[2,1-c][1,4]benzoxazine-1,2,4-triones react with N-unsubstituted and N-substituted 3-amino-5,5-dimethylcyclohex-2-en-1-ones to give 3′-aroyl-4′-hydroxy-1′-(o-hydroxy-phenyl)-6,6-dimethyl-6,7-dihydrospiro[indole-3,2′-pyrrole]-2,4,5′(1H,1′H,5H)-triones. The molecular and crystalline structure of the 1-cyclohexyl-substituted derivative was studied by X-ray analysis.     

Recyclization of 1,3-dialkyl-6-nitro-1<Emphasis Type="Italic">H</Emphasis>-imidazo[4,5-<Emphasis Type="Italic">b</Emphasis>]pyridine-2,5(3<Emphasis Type="Italic">H</Emphasis>,4<Emphasis Type="Italic">H</Emphasis>)-diones into imidazole derivatives

Treatment of 5-amino-1,3-dialkyl-2,3-dihydro-1H-imidazo[4,5-b]pyridin-2-ones with sodium nitrite in aqueous HCl gave 1,3-dialkyl-1H-imidazo[4,5-b]pyridine-2,5(3H,4H)-diones which were nitrated with potassium nitrate in sulfuric acid to 6-nitro derivatives, and the latter underwent recyclization into 4-amino-1,3-dialkyl-5-(1H-pyrazol-5-yl)-2,3-dihydro-1H-imidazol-2-ones by the action of hydrazine hydrate.     

Synthesis of 4-trifluoromethyl-3,4-dihydro-1,3,5-triazino[2,1-<Emphasis Type="Italic">a</Emphasis>]isoindol-2-ones by cyclocondensation of 1-aryl-1-chloro-2,2,2-trifluoroethyl isocyanates with 3-amino-1-arylimino-1<Emphasis Type="Italic">H</Emphasis>-isoindoles

4-Trifluoromethyl-3,4-dihydro-1,3,5-triazino[2,1-a]isoindol-2-ones were prepared by reaction of 1-aryl-1-chloro-2,2,2-trifluoroethyl isocyanates with 3-amino-1-arylimino-1H-isoindoles in the presence of triethylamine. In some events alongside the main product isomeric 2-trifluoromethyl-2,3-dihydro-1,3,5-triazino[2,1-a]isoindol-4-ones were obtained. The regioselectivity of the reaction is affected by sterical and electronic characteristics of substituents and by temperature.     

Cross-recyclization of 4-aryl-2,6-diamino-4<Emphasis Type="Italic">H</Emphasis>-thiopyran-3,5-dicarbonitriles with 1-morpholino-1-cyclopentene: New route to 4-aryl-2-thioxo-2,5,6,7-tetrahydro-1<Emphasis Type="Italic">H</Emphasis>-[1]pyrindine-3-carbonitriles and their derivatives

Reaction of 4-aryl-2,6-diamino-4H-thiopyran-3,5-dicarbonitriles with 1-morpholino-1-cyclopentene led to the formation of 4-aryl-2-thioxo-2,5,6,7-tetrahydro-1H-[1]pyrindine-3-carbonitriles used in the synthesis of substituted 2-alkylsulfanyl-4-aryl-6,7-dihydro-5H-[1]pyrindine-3-carbonitriles and 3-amino-4-aryl-6,7-dihydro-5H-cyclopenta[bthieno[3,2-e]pyridines.     

Synthesis of new imidazo[2,1-<Emphasis Type="Italic">b</Emphasis>][1,3]thiazole derivatives from 2-amino-4-(2,2-dichlorovinyl)-1,3-thiazole and <Emphasis Type="Italic">N</Emphasis>-(2,2-dichloro-2-phenylethylidene)arenesulfonamides

2-Amino-4-(2,2-dichlorovinyl)-1,3-thiazole reacted with highly electrophilic N-(2,2-dichloro-2-phenylethylidene)- and N-(2,2,2-trichloroethylidene)arenesulfonamides through the exocyclic amino group to give products of nucleophilic addition to the azomethine bond, N-[2,2-di(or 2,2,2-tri)chloro-1-(1,3-thiazol-2-ylamino)ethyl]arenesulfonamides in good yields. Intramolecular heterocyclization of the latter afforded N-[3-(2,2-dichloroethyl)-6-phenylimidazo[2,1-b][1,3]thiazol-5-yl]arenesulfonamides.     

Alkenyl derivatives of 5-nitro-2-pyridone: Synthesis and halocyclization

Alkylation of 5-nitro-2-pyridone by alkenyl halides in acetone in the presence of K₂СО₃ proceeds with generation of a mixture of N- and О-derivatives with N-isomer prevailing. 1-Allyl- and 1-methylallyl-5-nitro-2-pyridone react with halogens with the formation of 2-halomethyl-6-nitro-2,3-dihydrooxazolo[3,2-a]-pyridinium halides. 1-Prenyl-5-nitro-2-pyridone reacts with bromine with the formation of 3-bromine-2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium bromide, and with iodine giving 2,2-dimethyl-7-nitro-3,4-dihydro-2Н-pyrido[2,1-b][1,3]oxazinium triiodide.     

Synthesis and heterocyclization of 2-{[2-(4-bromophenyl)-2-oxoethyl]sulfanyl}pyrimidin-4(3<Emphasis Type="Italic">h</Emphasis>)-ones

Alkylation of sodium 4(5)-alkyl-6-oxo-1,6-dihydropyrimidine-2-thiolates with 2-bromo-1-(4-bromophenyl)ethan-1-one afforded 2-{[2-(4-bromophenyl)-2-oxoethyl]sulfanyl}pyrimidin-4(3H)-ones. Analogous reaction with sodium 4-trifluoromethyl-6-oxo-1,6-dihydropyrimidine-2-thiolate gave a mixture of 2-{[2-(4-bromophenyl)-2-oxoethyl]sulfanyl}-4-(trifluoromethyl)pyrimidin-4(3H)-one and its intramolecular cyclization product, 3-(4-bromophenyl)-3-hydroxy-7-trifluoromethyl-2,3-dihydro[1,3]thiazolo[3,2-a]-pyrimidin-5-one.     

Three-Component Spiro Heterocyclization of Pyrrolediones with Malononitrile and Cyclic Enols

Ethyl 4,5-dioxo-2-phenyl-4,5-dihydro-1H-pyrrole-3-carboxylates reacted with malononitrile and five-membered cyclic enols, indan-1,3-dione and cyclopentane-1,3-dione to give 1-substituted ethyl 2-amino-3- cyano-2′,5-dioxo-5′-phenyl-1′,2′-dihydro-5H-spiro[indeno[1,2-b]pyran-4,3′-pyrrole]-4′-carboxylates and ethyl 2-amino-3-cyano-2′,5-dioxo-5′-phenyl-1′,2′,6,7-tetrahydro-5H-spiro[cyclopenta[b]pyran-4,3′-pyrrole]-4′-carboxylates, respectively.     

Fluorine-containing heterocycles: XVI. Reactions of tetrafluorobenzoyl isothiocyanate with hydrazines and their derivatives

Fluorinated derivatives of 4H-1,3-benzothiazin-4-one, [1,2,4]triazolo[4,3-a]pyrimidine, [1,2,4]triazolo[3,4-b][1,3]benzazoles, and 1,5-dihydro-1,2,4-triazole-5-thione were synthesized by addition of hydrazines and their derivatives to tetrafluorobenzoyl isothiocyanate, followed by cyclization of intermediate thiosemicarbazides.     

Synthesis of 2-(halomethyl)-3,4-dihydro-2<Emphasis Type="Italic">H</Emphasis>-pyrido[2,1-<Emphasis Type="Italic">b</Emphasis>][1,3]oxazinium halides

Alkylation of pyridin-2(1H)-one and 5-nitropyridin-2(1H)-one with 4-bromobut-1-ene afforded a mixture of N- and O-butenyl derivatives. 1-(But-3-en-1yl)pyridin-2(1H)-one and 1-(but-3-en-1-yl)-5-nitropyridin- 2(1H)-one reacted with bromine and iodine to give 2-(halomethyl)-3,4-dihydro-2H-pyrido[2,1-b][1,3]-oxazinium halides.     

Cyclocondensation of <Emphasis Type="Italic">N</Emphasis>-aryl-3-oxobutanethioamides with 2-aminoimidazole and 2-aminobenzimidazole

Cyclization of N-aryl-3-oxobutanethioamides with 2-aminoimidazole and 2-aminobenzimidazole gave 7-methyl-5,8-dihydroimidazo[1,2-a]pyrimidine-5-thione or 2-methylpyrimido[1,2-a]benzimidazole-4(1H)-thione and 4-(arylamino)-2-methylpyrimido[1,2-a]benzimidazoles whose ratio depends on the nature of aryl substituents in the initial butanethioamides and on the presence of a protic solvent.