Synthesis of 2-Arylimidazo[1, 2-a]pyrimidines in Ionic Liquids

Room temperature ionic liquids were used as a “green“ recyclable alternative to conventional solvents in the synthesis of pharmaceutically useful compounds 2-arylimidazo[1, 2-a]pyrimidines through Tschotschibabin reaction of a-bromoacetophenones with 2-aminopyrimidine in good yields.     

Synthesis of 2-Arylimidazo[l, 2-a]pyrimidines in Ionic Liquids

Room temperature ionic liquids were used as a "green" recyclable alternative to conventional solvents in the synthesis of pharmaceutically useful compounds 2-arylimidazo[1, 2-a] pyrimidines through Tschotschibabin reaction of a-bromoacetophenones with 2-aminopyrimidine in good yields.     

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.     

Acetylene-driven multi-molecular assemblies of high complexity: imidazo[1,2-a]pyridines and 5-chloro-N-[2-(imidazo[1,2-a]pyridin-6-yl)vinyl]pyridin-2-amine

Acetylene reacts with 2-aminopyridines in the superbase system KOBu^t/DMSO (the initial acetylene pressure ∼8 atm, 80 °C, 5 min) to give 2,3-dimethylimidazo[1,2-α]-pyridines in up to 60% yields. In the case of 2-amino-5-chloropyridine, along with ‘normal’ product, (Z)-5-chloro- N-[2-(2,3-dimethylimidazo[1,2-α]pyridin-6-yl)vinyl]pyridin-2-amine is formed in 40% yield. These multi-molecular assemblies involve parallel nucleophilic addition of N-centered anions to the triple bond and ethynylation of the forming C=N bond.     

Synthesis of 3-dimethylphenylsilyl-substituted pyrido[1,2-a]benzimidazoles

Reductive cyclization of 1-(2,4-dinitrophenyl)-3-methyl-4-dimetkylphenyisililpyridinium chloride by the action of phenylkydrazine or hydrogen in the presence of Pd/C gave, for the first time, 7-nitro (amino)-3 dimethylphenylsilylpyrido[l, 2-affienzimidazoles.Russian University of the Friendship of Nations, Moscow, 117923. Translated from Khimiya Geterots ikl icheskikh Soedinenii, No, 3, pp. 338–341, March, 1996. Original article submitted November 27, 1995.     

Synthesis of pyrrolo[1,2-a]indoles from 2-arylidene-3-indolinones

Chemistry of Heterocyclic Compounds -     

3-Substituted 2-trifluoromethylimidazo [1,2-a] pyridines

3-Fluoro-2-trifluoromethylimidazo[1,2-a]pyridines were obtained by reactions of hexafluoroacetone 2-pyridylimines with trimethyl phosphite and studied in reactions with sodium methoxide. This gave the corresponding 3-methoxy-2-trifluoromethylimidazo[1,2-a]pyridines.     

A Facile Synthesis of Pyrido [1,2-a] Benzimidazoles

The synthesis and characterisation of some of the new pyrido [1,2-a] benzimidazoles from 1H-benzimidazole-2-acetonitrile and diethyl ethoxy methylene malonic ester.     

3-Hydroxypyrimido[1,2-a]benzimidazoles

The oxidation of aromatic derivatives of 1,4- and 3,4-dihydropyrimido[1,2a]benzimidazoles gave the corresponding 3-hydroxy-3,4-dihydro derivatives and the dehydrogenation of these compounds was carried out. An x-ray diffraction structural analysis was carried out on 2-(4-dimethylaminophenyl)-3-hydroxy-4-phenyl-3,4-dihydropyrimido[1,2a]benzimidazole.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 688–693, May, 1993.     

2-吡啶基咪唑并[1,2-a]吡啶的水中合成

2-乙酰基吡啶1经溴化反应后得到2-(2-溴乙酰基)吡啶氢溴酸盐2,2在水中与NaHCO3发生中和反应生成2-(2-溴乙酰基)吡啶,不经分离直接于水中和2-氨基吡啶衍生物3a-3h反应生成2-吡啶基咪唑并[1,2-a]吡啶4a-4h.采用核磁共振谱仪、红外光谱仪及质谱仪表征了产物的结构.结果表明,利用该方法可以在温和的反应条件下高产率得到目标产物,且方法操作简便、对环境友好.     

Fused indoles. 2. Synthesis and reactions of imidazo[1,2-a]- and pyrimido[1,2-a]-indoles

The alkylation of 2-chloroindole-3-carboxaldehyde ( 1 ) and 3-acetyl-2-chloroindole ( 5 ) with 3-chloro-N,N-dimethyl-1-propylamine, 3-chloro-N,N-diethyl-1-propylamine and 2-chloro-N,N-dimethyl-1-ethylamine is described. Following alkylation, demethylation occurs and furnishes imidazo[1,2,-a]- and pyrimido[1,2-a]indoles ( 3a,6,8,10 ). Pyrimido-indole 3a , on treatment with lithium aluminum hydride, furnishes the bis-indole 12 . Analogous reaction with diborane affords the reduced product 14 , while reaction with methyllithium yields the deformylated product 13 . Spectral data of the resulting compounds are also discussed.