Synthesis of 1,3-dialkyl-5-(pyrrol-1-yl)-1,3-dihydro-2H-imidazo[4,5-b]pyridin-2-ones

Russian Journal of Organic Chemistry -     

Quaternization of 1H-imidazo[4,5-b]pyridine and 4-methyl-4H-imidazo[4,5-b]pyridine

Unsubstituted imidazo[4,5-b]pyridine adds methyl iodide to the pyridine N atom. Treatment of the resulting iodide with base forms 4-methyl-4H-imidazo[4,5-b]pyridine. This nucleophile can readily add methyl iodide to form only one salt, 1,4-dimethylimidazo[4,5-b]pyridinium iodide.L. M. Litvinenko Institute of Physical Organic Chemistry and Coal Chemistry, Ukraine Academy of Sciences, Donetsk 340114. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1232–1233, September, 1994. Original article submitted june 17, 1994.     

1H-imidazo[4,5-b] pyrazines. 1. 2-Alkyl derivatives

A group of 2-alkyl-1H-imidazo[4,5-b]pyrazines were prepared by condensing diamonpyrazines with acid, acid chloride or acid anhydride.     

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.     

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.     

1H-imidazo[4,5-b]pyrazines. III. 2-Thiols and derivatives

1H-Imidazo[4,5-b]pyrazine-2-thiols were prepared. Their chlorination, alkylation and cyclization reactions are discussed.     

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 .     

1H-imidazo[4,5-b] pyrazines. II. 2-carboxylic acid derivatives

Methods for the preparations of 1H-imidazo[4,5-b]pyrazine-2-carboxylic acid and derivatives are reported.     

A novel synthetic route to 1,2-dimethyl-5-phenyl-1H-imidazo[4,5-b]pyridin-7-ol

Heating a mixture of 4-amino-1,2-dimethyl-1H-imidazole-5-carboxylic acid ethyl ester with ethyl benzoyl acetate resulted in the formation of 8-ethoxycarbonyl-6,7-dimethyl-4-oxo-2-phenylimidazo[1,5-a]pyrimidin-5-ium, hydroxide, inner salt. This compound was then transformed into 1,2-dimethyl-5-phenyl-1H-imidazo-[4,5-b]pyridin-7-ol via several intermediates. A number of structurally interesting compounds were also isolated during the course of this work. Thus, the target ring system was formed by a circuitous series of ring-chain tautomerizations/rearrangements.     

Crystal structure of 1-(diphenylmethylene)-2-(thiazolo[4,5-b]pyridin-2-yl)hydrazine

The 1-(diphenylmethylene)-2-(thiazolo[4,5-b]pyridin-2-yl)hydrazine compound (IV) is synthesized based on a 3-amion-2-chloropyridine precursor and characterized by single crystal X-ray diffraction. The structural analysis reveals that compound IV belongs to the monoclinic system, space group P2₁/c, a = 11.869(5) Å, b = 13.155(6) Å, c = 10.970(5) Å, β = 102.431(5)°, V = 1672.6(12) ų, Z = 4. In the crystal structure, the molecular species are linked by intermolecular N-H...N hydrogen bonds into onedimensional chains.     

An improved synthesis of 3,8-dimethyl-3H-imidazo[4,5-f]quinoxalin-2-amine ("MeIQx") and its 2-14C-labelled analogue

The highly mutagenic title compound (MeIQx) was prepared in 21% overall yield from 4-fluoro-o-phenylenediamine. The 3,7-dimethyl isomer may be obtained as a minor by-product. The 14C-label was introduced in the last step through cyclization with [14C]cyanogen bromide. An alternative synthesis of MeIQx from p-fluoroaniline avoided the separation of isomers but gave poorer yield.     

Synthesis of the potent mutagen 3,5,8-trimethyl-3H-imidazo[4,5-f]quinoxalin-2-amine

The mutagenic title compound (5,8-DiMeIQx) was synthesized by two different routes: from 2-methyl-4,6-dinitroaniline; and from 4-chloro-2-methyl-6-nitroaniline. The latter and more convenient route involved 2,1,3-benzoselenadiazole intermediates.     

新型2-(2-羧基苯基)咪唑[4,5-f][1,10]邻菲咯啉的合成及其荧光性能

以1,10-邻菲咯啉和邻羧基苯甲醛为原料,经氧化和缩合反应合成了一种新型的桥连配体——2-(2-羧基苯基)咪唑[4,S-f][1,10]邻菲咯啉(1),其结构经1H NMR,IR,MS和元素分析表征.用FL研究了1的荧光性能,结果表明,1具有较强的荧光,发光纯度较好.     

Synthesis and anticonvulsant activity of 3H-imidazo[4,5-c]-pyridazine, 1H-imidazo[4,5-d]pyridazine and 1H-benzimidazole analogues of 9-(2-fluorobenzyl)-6-methylamino-9H-purine

The 3H-imidazo[4,5-c]pyridazine, 1H-imidazo[4,5-d]pyridazine, and 1H-benzimidazole analogues of the potent anticonvulsant purine 9-(2-fluorobenzyl)-6-methylamino-9H-purine (1, 78U79) were synthesized and tested for anticonvulsant activity. The 3H-imidazo[4,5-c]pyridazines 8 and 9 were prepared in five stages from 3,4,5-trichloropyridazine (2) . The 1H-imidazolo[4,5-d]pyridazine 15 was synthesized in four stages from 5-[(benzyloxy)methyl]-1,5-dihydro-4H-imidazo[4,5-d] pyridazin-4-one (10a) . The benz-imidazole analogues 18 and 20 were prepared from 2,6-dinitroaniline in three stages. These compounds were one-tenth or less as active as 1 in protecting rats against maximal electroshock-induced seizures.     

Synthesis and lanthanide coordination chemistry of 2-[(phosphinoyl)methyl]-4,5-dihydrooxazole and 2-[(phosphinoyl)methyl]benzoxazole ligands

Syntheses for [(diphenylphosphinoyl)methyl]-4,5-dihydrooxazole (2) and [(diarylphosphinoyl)methyl]benzoxazoles [aryl = phenyl (3), tolyl (4), 2-trifluoromethylphenyl (5) and 3,5-bis(trifluoromethyl)phenyl (6)] have been developed. Each ligand has been characterized by spectroscopic methods and single crystal X-ray diffraction analyses have been completed for 2, 3, 4 and 5. The coordination chemistry of the ligands with Nd(NO₃)₃ and Yb(NO₃)₃ has been examined and structure determinations for [Nd(2)₂(NO₃)₃(CH₃OH)], [Nd(2)₂(NO₃)₃], [Yb(3)₂(NO₃)₃(H₂O)]·0.5(CH₃OH), [Nd(3)₂(NO₃)₃]·3(CHCl₃), [Nd(4)₂(NO₃)₃(H₂O)], [Yb(4)₂(NO₃)₃(H₂O)] and [Yb(5)₂(NO₃)₃(H₂O)]·0.5(CH₃CN) are reported. Depending upon conditions, the ligands act as monodentate PO or bidentate, chelating PO,N donors.     

2-(2-Furyl)-1(3)H-imidazo[4,5-f]quinoline. Synthesis and electrophilic substitution reactions

2-(2-Furyl)-1(3)H-imidazo[4,5-f]quinoline was synthesized by the Weidenhagen reaction of quinoline-5,6-diamine with furfural. Its alkylation with methyl iodide in the system KOH-DMSO gave two isomeric N-methyl derivatives, 2-(2-furyl)-1-methyl-1H- and 2-(2-furyl)-3-methyl-3H-imidazo[4,5-f]quinolines, the latter prevailing. 2-(2-Furyl)-3-methyl-3H-imidazo[4,5-f]quinoline was brought into electrophilic substitution reactions: bromination, nitration, formylation, acylation, sulfonation. Depending on the reaction conditions, electrophilic attack could be directed at both furan ring and quinoline fragment.