Synthesis of disubstituted imidazo[4,5-b]pyridin-2-ones

Regioselective palladium-catalyzed amination of 2-chloro-3-iodopyridine followed by a subsequent palladium-catalyzed amination leads to 2,3-diaminopyridines. Treatment with triphosgene affords highly functionalized unsymmetrical imidazo[4,5-b]pyridin-2-ones in just three synthetic steps. A two-step synthesis of pseudosymmetrically disubstituted imidazo[4,5-b]pyridin-2-ones, 1,4-disubstituted pyrido[2,3-b]pyrazinediones, and 1,3-disubstituted thiadiazolo[3,4-b]pyridin-2-ones is also described.     

A synthetic entry to furo[2,3-b]pyridin-4(1H)-ones and related furoquinolinones via iodocyclization

[reaction: see text] N-Methyl-4-alkoxy-3-alkynylpyridin-2(1H)-ones readily undergo iodine-promoted 5-endo-heteroannulation under mild conditions to 3-iodofuropyridinium triiodide salts in moderate to good yields. The latter may be dealkylated in situ upon exposure to an iodide anion to provide the corresponding 3-iodofuro[2,3-b]pyridin-4(1H)-ones. The same strategy applies to the formation of furo[2,3-b]quinolin-4(9H)-ones.     

Synthesis of 1-and 3-substituted imidazo[4,5-b]pyridin-2-ones

1-and 3-Substituted imidazo[4,5-b]pyridin-2-ones were synthesized by heating equimolar amounts of 3-amino-2-chloropyridine or 2-chloro-3-methylaminopyridine, urea, and the corresponding arylamine at 150–210°C. The reaction of 3-amino-2-chloropyridine with urea and p-phenylenediamine or p,p′-diaminobiphenyl at a ratio of 2:2:1 under analogous conditions gave 1,4-bis-(2-oxoimidazo[4,5-b]pyridin-3-yl)benzene or 1,4-bis(2-oxoimidazo[4,5-b]pyridin-3-yl)biphenyl, respectively.     

The synthesis of novel 1-hetarylmethylidene-4-sulfanylfuro-[3,4-c]pyridin-3(1H)-ones

Chemistry of Heterocyclic Compounds - 1-Hetarylmethylidene-4-sulfanylfuro[3,4-c]pyridin-3-ones were accessed from 4-thioxo-4,5-dihydrofuro[3,4-c]pyridin-3(1H)-one employing a condensation reaction...     

Synthesis of 2-aryl-5H-[1,3,4]-thiadiazolo[2,3-b]quinazolin-5-ones

3-Amino-2-thioxo-1,2,3,4-tetrahydroquinazolin-4-ones were converted into 2-aryl-5H-[1,3,4]thiadiazolo[2,3-b]quinazolin-5-ones on treatment with carboxylic acids and POCl₃. 3-Arylmethylidenamino-2-thioxo-1,2,3,4-tetrahydroquinazolin-4-ones also cyclized to 2-aryl-5H-[1,3,4]thiadiazolo[2,3-b]quinazolin-5-ones when oxidized with potassium chlorate in acetic acid, but on heating they were deaminated to give 2-thioxo-1,2,3,4-tetrahydroquinazolin-4-one and aryl nitriles. __________ Translated from Khimiya Geteotsiklicheskikh Soedinenii, No. 5, 787–791, May, 2006.     

Synthesis and properties of 4-(3-aminothieno-[2,3-b]pyridin-2-yl)coumarins

Substituted 4-[(3-cyanopyridin-2-yl)thiomethyl]coumarins have been synthesized by the alkylation of 2-mercapto-4,6-dimethylnicotinonitrile with 4-chloromethylcoumarins. Substituted 4-(3-amino-thieno[2,3-b]pyridin-2-yl)coumarins have been obtained by a subsequent intramolecular condensation of the methylene and cyano groups. 6H-Chromeno[4,3-d]thieno[3,2-b:5,4-b']dipyridin-6-ones were isolated as a result of the interaction of these compounds with aldehydes, and their aminomethyl derivatives were synthesized.     

苯并吡喃[3,4-c]吡啶-5-酮类化合物的合成

以4-酮-3-甲酸甲酯哌啶盐酸盐为原料, 通过分子间环加成和N-烷基化反应, 合成了一系列潜在的多巴胺D₄受体配基苯并吡喃[3,4-c]吡啶-5-酮类化合物, 并用¹H NMR, IR, ESI-MS, 元素分析对其进行了表征.     

Syntheses of optically active tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones and hexahydroimidazo[1,2-a]pyridin-2(3H)-ones

The reactions of (2S)-2-amino-2-substituted-N-(4-nitrophenyl)acetamides 16a-c, succindialdehyde (13), and benzotriazole afforded enantiopure (3S,5R,7aR)-5-(1H-1,2,3-benzotriazol-1-yl)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 17a-c, which were converted by sodium borohydride into (3S,7aR)-3-substituted-1-(4-nitrophenyl)tetrahydro-1H-pyrrolo[1,2-a]imidazol-2-ones 18a-c. Chiral (2S)-2-amino-2-substituted-N-(4-methylphenyl)acetamides 12a-d, easily prepared in two steps from N-Boc-alpha-amino acids 10a-d, similarly reacted with glutaraldehyde (20) and benzotriazole to generate 5-benzotriazolyl-3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 21a-d, which were converted by sodium borohydride directly into optically active 3-substituted-hexahydroimidazo[1,2-a]pyridin-2(3H)-ones 22a-d.     

Synthesis of 5H[l]benzopyrano[3,4-b]pyridin-5-one and its derivatives

3-Aminocoumarin undergoes the Skraup reaction to give a new ring system, 5H[l]benzo-pyrano[3,4-b]pyridin-5-one (IVa). When 3-aminocoumarin was condensed with the ethoxy methylene derivatives of active methylene compounds, ethyl acetoacetate, and dimethyl acetylenedicarboxylate, the intermediates Vla-VIf were formed which on thermal cyclizations afforded other derivatives of 5H[l ]benzopyrano[3,4-b]pyridin-5-one (IVb-IVf). The nitration of IVa gave IVg.     

New syntheses of condensed heterocycles from isoxazole derivatives. V. Pyrrolo[3,4-b ]pyridin-4-ones

Hydrogenolysis with Raney-Nickel or iron powder in acetic acid of 2,5-diphenyl-4-nitro-3-(3,5-R,R-4-isoxazolyl)pyrrolyl ketones, prepared by the Grignard reaction of 2,5-diphenylpyrrole and 3,5-R,R-4-isoxazolecarboxilic acid chlorides followed by nitration, afforded directly the desired 6H-pyrrolo[3,4-b ]pyridin-4-ones.     

Reaction of 4-aminoimadazo[4.5-c]pyridin-2-ones with α-bromomethylketones

The reactions of 4-amino derivatives of imidazo[4.5-c]pyridin-2-ones with -bromomethylketones have been studied. Depending on the nature of the reagents and the reaction conditions, either 5-acylmethyl salts of the starting amine or 2-substituted imidazo[4.5-c]imidazo[1,2-a]pyridin-8-ones can be obtained. The latter compounds are also easily obtained by treatment of the 5-acylmethyl salts with alkali.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 227–232, February, 1986.     

Synthesis of 1,2,3,4-tetrahydro-5H-[1]benzopyrano[3,4-c]pyridin-5-ones. I. 3-unsubstituted compounds

Synthesis of 1,2,3,4-tetrahydro-5H-[1]benzopyrano[3,4-c]pyridin-5-ones via a Pechmann condensation of 3-carbethoxy-1-methyl-4-piperidone with various phenols is described. The limitations of this method are discussed. Synthesis of the parent ring system 3a via reduction of 1,2,3,4-tetrahydro-3-(phenylmethyl)-8-[(1-phenyl-1H-tetrazol-5-yl)oxy]-5H-[1]benzopyrano[3,4-c]pyridin-5-one ( 5 ) is also described.     

A short and general synthesis of 1,3-dihydro-6-heteroaryl-5-perfluoroalkyl-2H-imidazo[4,5-b]pyridin-2-ones

Trifluoro or pentafluoroacylation of heteroaryl-enamines 2a,b gave the corresponding perfluoroacylated heteroaryl-enamines 3a-c . Heating the latter compounds with diethyl iminomalonate gave 2-amino-3-pyridinecarboxylates 4a-c . Hydrolysis to the free acids 5a-c , and reaction with diphenylphosphoryl azide afforded the desired 1,3-dihydro-6-heteroaryl-5-perfluoroalkyl-2H-imidazo[4,5-b]pyridin-2-ones 6a-c .     

Convenient synthesis of pyrazolo[3,4-b]pyridin-3-ones and pyrazolo[3,4-b]pyridine-5-carbaldehyde using vinamidinium salts

An expedient method for the synthesis of 2-phenyl-5-aryl-2,3-dihydropyrazolo[3,4-b]pyridin-3-ones and 2-phenyl-3-oxo-2,3-dihydropyrazolo[3,4-b]pyridine-5-carbaldehyde in a single-step via condensation of vinamidinium salts with 3-amino-1-phenyl-2-pyrazolin-5-one is described.     

An efficient synthesis of novel benzo[b]pyrido[3',2':4,5] thieno[2,3-e][1,6]naphthy-ridine-8-ones

An efficient method for the synthesis of novel benzo[b]pyrido[3',2':4,5] thieno[2,3-e][1,6] naphthyridine-8-one derivatives has been developed using a Pictet-Spengler reaction between 4-(3-aminothieno[2,3-b]pyridin-2-yl)quinoline-2-ones, which could be obtained from the alkylation of 4-bromomethylquinoline-2-ones with 3-cyanopyridine-2-thione followed by a Thorpe-Ziegler isomerization, and aromatic aldehydes under p-TsOH as catalysis in good yields.     

Synthesis and properties of 4-haloimidazo[4,5-c]pyridin-2-ones

Summary The nitro group in 4-nitroimidazo[4,5-c]pyridin-2-ones is rather labile and may be replaced upon heating with hydrohalic acids to give the corresponding 4-halides. A methyl group at N₍₃₎ leads to a sharp increase in the lability of the nitro group, but the isomeric 5-vitro derivatives do not react with hydrobromic or hydrochloric acids. Some reactions and transformations of 4-chloroimidazo[4,5-clpyridin-2-one are examined.Translated from Khimiya Getcrotsiklichcskikh Soedinenii, No. 8, pp. 1071-1075, August, 1994.     

5α-androstano [3,2-b]pyridines, 5α-androstano[17,16-b]pyridines and androst-4 and 5-eno[17,16-b]pyridines

A new synthesis of 5α-androstano[3,2-b]pyridin-17β-ol acetate (VIa) and 17-methyl-5α-androstano[3,2-b]pyridin-17β-ol (VIb), first reported by Shimizu, Ohta, Ueno, and Takegoshi, was achieved. The analogous 5α - androstano[17,16-b]pyridin-3β-ol (XII), 5α-androstano[17,16-b]pyridin-3-one (XIVa), and androst-4-eno[17,16-b]pyridin-3-one (XIVb) were also prepared. An illustration of the method follows. Condensation of 3β-hydroxy-5α-androstan-17-one (VIIa) with 3-(2-furyl)acrolein afforded 16-[3-(2-furyl)-2-propenylidene]-3β-hydroxy-5α-androstan-17-one (VIIIa), the oxime (IXa) of which was thermally cyclized to 5α-androstano[17,16-b]-6′-(2-furyl)pyridin-3β-ol (Xa). 3β-Hydroxy-5α-androstano[17,16-b]pyridine-6′-carboxylic acid (XI) was obtained by ozonolysis of Xa. Thermal decarboxylation of XI gave XII. Cinnamaldehyde was used in place of 3-(2-furyl)acrolein to give the corresponding phenylpyridines.     

Ammonium chloride-promoted four-component synthesis of pyrrolo[3,4-b]pyridin-5-one

A novel multicomponent synthesis of 5-aminooxazole starting from simple and readily available inputs is described. Thus, simply heating a methanol solution of an aldehyde 3, an amine 4, and an alpha-isocyanoacetamide 5 provided the 5-aminooxazole (1) in good to excellent yield. The reaction of 1 with alpha,beta-unsaturated acyl chloride 13 lead to the formation of pyrrolo[3,4-b]pyridin-5-one (2) in a single operation. A triple domino sequence, acylation/IMDA/retro-Michael cycloreversion, is involved in this new scaffold-generating reaction. After the observation that ammonium chloride can significantly accelerate the oxazole formation in toluene, a one-pot four-component synthesis of 2 is developed.     

On the preparation of substituted 4H- 1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones and 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles

The reaction of benzoyl isothiocyanates and methoxycarbonyl isothiocyanate with 4-amino-4,5-dihydro-3-(methylthio)-1,2,4-triazin-5-ones in acetonitrile gave several substituted 4H-1,3,4-thiadiazolo[2,3-c]-1,2,4-triazin-4-ones VIa-h instead of the expected thioureas. In addition, benzoyl isothiocyanate reacted with 4-amino-3-(methylthio)-5-(trifluoromethyl)-4H-1,2,4-triazole to give the benzoyl thiourea IX and with 4-amino-3-mercapto-5-(trifluoromethyl)-4H-1,2,4-triazole to give the bicyclic compound N-[3-(trifluoromethyl)-1,2,4-triazolo[3,4-b]-1,3,4-thiadiazol-6-yl]benzamide IX .     

Synthesis of 3-(Dialkylamino)-4-halofuro[3,4-c]pyridin-1(3H)-ones

Russian Journal of Organic Chemistry - The reaction of 4-halo-3-hydroxyfuro[3,4-c]pyridin-1(3H)-ones with acyclic and alicyclic secondary amines in ethyl acetate afforded the corresponding...