6- And 7-Substituted 4H-Pyrido[1,2-a] pyrimidin-4-ones. Synthesis via the Acid-catalyzed Isomerization of 2-(Acetoacetamido)pyridines

A novel procedure has been developed for converting a variety of substituted 2-(aceto-acetamido)pyridines into substituted 4H-pyrido[1,2-a]pyrimidin-4-ones. The reaction involves an acid-catalyzed isomerization of the 2-(acetoacetamido)pyridine derivatives into the corresponding enamines, under conditions that permit the latter to undergo cyclization to the 4-one, in situ. The method has been employed to prepare a number of hitherto unknown 2,6- and 2,7-di- and 2,7,9-trisubstituted 4H-pyrido[1,2-a]pyrimidin-4-ones.     

Synthesis of 4-(3-hydroxyalkyl)pyrimidines by ring transformation reactions of 2-alkylidenetetrahydrofurans with amidines

Domino reactions of amidines with 2-alkylidenetetrahydrofurans, prepared by cyclization of 1,3-dicarbonyl dianions or 1,3-bis-silyl enol ethers with various dielectrophiles, provided an efficient access to 4-(3-hydroxyalkyl)pyrimidines.     

Synthesis of 2-aryl-6-(4-bromophenyl)-4-(2,2-dichlorovinyl)pyridines with the use of 1-aryl-5,5-dichloropenta-2,4-dien-1-ones

Heating 1-aryl-5,5-dichloropenta-2,4-dien-1-ones with 4-bromophenacylpyridinium bromide in AcOH in the presence of AcONH₄ gave 2-aryl-6-(4-bromophenyl)-4-(2,2-dichlorovinyl)pyridines. The reaction products were structurally characterized by¹H and¹³C NMR spectroscopy. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 955–957, May, 2000.     

Synthesis and hydrolytic cleavage of 1-aryl-5-cyano-6-(2-dimethylaminovinyl)-4-oxo(thioxo)-1,4-dihydropyrimidines

1-Aryl-5-cyano-6-(2-dimethylaminovinyl)-4-oxo-1,4-dihydropyrimidines and their 4-thioxo analogs, which were prepared in three steps from cyanoacetamide and cyanothioacetamide, respectively, were subjected to hydrolysis. In aqueous AcOH, hydrolysis of N-(dimethylaminomethylene)-2-cyano-5-dimethylamino-2,4-pentadieneamide derivatives containing amino groups at position 3 afforded formylpyridones. The reaction of 2-cyano-3-dimethylaminothiocrotonamide with DMF dimethyl acetal gave rise to 3-cyano-4-dimethylamino-2-methylthiopyridine.     

The Synthesis of 2-Amino-4-(4-imidazolyl)pyridines

A general synthetic scheme for the preparation of 2-amino-4,(4-imidazolyl)pyridines, potential histamine H₂ antagonists, is described. The synthesis is based on the Neber rearrangement of l,(4-pyridyl)l-alkanone oxime 0-tosylates to the appropriate α-aminoketones or α-aminoketals, which are then converted to the corresponding imidazoles. The reaction of Grignard reagents with 2-chloroisonicotinonitrile, as well as nucleophilic displacement of chloride by amines on 2-chloroisonicotinonitrile and derivatives, are discussed in relation to the preparation of the ketone intermediates.     

Synthesis of 2-(4-cyanophenyl)-5-(4-n-alkyl- and alkoxyphenyl) pyridines

New liquid-crystalline 2-(4-cyanophenyl)-5-(4-alkyl- and alkoxyphenyl)pyridines were obtained by condensation of 1-dimethylamino-3-dimethylimmonia-2-(4-alkyl- or alkoxyphenyl)-1-propene perchlorates with 4-cyanoacetophenone and subsequent conversion of the 1-dimethylamino-2-(p-alkyl- or alkoxyphenyl)-4-(p-cyanobenzoyl)-1,3-butadienes to 5-(4-alkyl- or alkoxyphenyl)-2-(4-cyanophenyl)pyrylium perchlorates and refluxing of the latter with ammonium acetate in acetic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1392–1394, October, 1985.     

A Short Synthesis of 4- and 6-Azaindol-2(3H)-ones

Although indol-2(3H)-ones possess a wide range of pharmacological¹ and microbiological² activities, the corresponding azaindol-2(3H)-ones have stimulated little interest. Successful syntheses have been reported for the title compounds^3,4 involving several stages which in our hands gave a variety of side products, especially in the hydrogenation stage.     

Synthesis of 5-Alkyl(aryl)-2-alkylsulfanyl(alkoxy)-4-hydroxy-6H-1,3-oxazin-6-ones

Alkyl carbamates and S-alkyl thiocarbamates react with substituted malonyl dichlorides in boiling benzene to give the corresponding 2,5-substituted 4-hydroxy-6H-1,3-oxazin-6-ones. The reaction of S-methyl thiocarbamate with unsubstituted malonyl dichloride in boiling diethyl ether or benzene leads to formation of S-methyl (3-methylsulfanylaminocarbonyl-3-oxopropionyl)thiocarbamate and is not accompanied by cyclization, whereas in boiling toluene 4-hydroxy-2-methylsulfanyl-6H-1,3-oxazin-6-one is obtained.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 468–472.Original Russian Text Copyright © 2005 by Lalaev, Yakovlev, Zakhs.     

Efficient Synthesis of 2-(8-Quinolinoxy)-4H-imidazolin-4-ones

IntroductionMany N- heterocycles including 4H - imidazolin-4- ones show bactericidal and fungicidal activities,especially those with a 2 - alkoxyl substituent[1— 5] .The efforts to discover the new biologically activederivatives reflected by the still important numberof publications and patents have been devoted tothe subject[6— 11] .For example,some 2 - amino or 2 -alkylthio substituted 4H- imidazolin- 4- ones showsignificant antifungal and antibacterial activi-ties[7— 9] ,whereas others …     

On the reactivity of 6-acetyl-7-(2-dimethylaminovinyl)pyrazolo[1,5-a]pyrimidines with 1,3- and 1,4-bisnucleophiles

Reaction of 6-acetyl-7-(2-dimethylaminovinyl)pyrazolo[1,5-a]pyrimidine 1 with 1,3- and 1,4-bisnucleophiles has been investigated; obtainment of new polycyclic heterocyclic derivatives is reported. A convenient procedure leading to new pyrazolo[1,5-a]quinazolines is described; a modest bioactivity of these compounds against two human tumor cell lines was also ascertained.     

Synthesis of 5-n-alkyl-2-(trans-4-n-alkylcyclohexyl)pyridines

The cyclization of trans-1-acrylyl-4-n-alkylcyclohexanes with trans-1-N-piperidino-1-alkenes was used to synthesize 3-n-alkyl-6-(trans-4-n-alkyl-cyclohexyl)-3,4-dihydro-2-N-piperidino-2H-pyrans, which were converted under the influence of hydroxylamine to 5-n-alkyl-2-(trans-4-n-alkylcyclohexyl)-pyridines. Problems in the stereochemistry of the cyclohexane derivatives in the investigated scheme of synthesis were examined.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 643–647, May, 1984.     

Ring transformation of 5-amino (or acylamino)-6-hydroxy (or benzoyloxy)methylpyrimidin-4(3H)-ones into 1H-imidazoles

Treatment of 5-acylamino-6-hydroxy (or benzoyloxy)methyl-3-phenylpyrimidin-4(3H)-one 5,10 with 5% aqueous sodium hydroxide in ethanol gave 2-alkyl-5-hydroxymethyl-4-phenylcarbamoyl-1H-imidazoles 7,11 . Oxidation of 5-amino-6-benzoyloxymethyl-3-phenylpyrimidin-4(3H)-one 9 in the presence of copper( II ) chloride in alcohol gave 2-alkoxy-5-alkoxymethyl-4-phenylcarbamoyl-1H-imidazoles 12a,b accompanied by 5-amino-6-alkoxymethyl-3-phenylpyrimidin-4(3H)-ones 13a,b.     

2-(4-甲硫基苯氧基)－4H－咪唑啉-4-酮衍生物的合成及生物活性

咪唑啉酮;2-(4-甲硫基苯氧基)－4H－咪唑啉-4-酮衍生物的合成及生物活性     

Synthesis of 2-(1-alkoxyvinyl)pyridines

2-(1-Bromovinyl)pyridine, 2-ethynylpyridine, 2-(1-alkoxyvinyl)pyridines, and 2-(2-alkoxyvinyl)pyridines (the cis and trans isomers) were detected in the reaction mixture by mass spectrometry in the reaction of 2-vinylpyridine with bromine with subsequent dehydrobromination of the addition product with an alcohol solution of alkali. The conditions for the preparation of chromatographically pure compounds were found.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 647–650, May, 1978.     

Doubly Decarboxylative Synthesis of 4-(Pyridylmethyl)chroman-2-ones and 2-(Pyridylmethyl)chroman-4-ones under Mild Reaction Conditions

The doubly decarboxylative Michael–type addition of pyridylacetic acid to chromone-3-carboxylic acids or coumarin-3-carboxylic acids has been developed. This protocol has been realized under Brønsted base catalysis, providing biologically interesting 4-(pyridylmethyl)chroman-2-ones and 2-(pyridylmethyl)chroman-4-ones in good or very good yields. The decarboxylative reaction pathway has been confirmed by mechanistic studies. Moreover, attempts to develop an enantioselective variant of the cascade are also described.     

2-(4-甲硫苯氧基)-3-(4-甲苯基)-4H-咪唑啉-4-酮衍生物的合成及杀菌活性(Ⅱ)

用烯基膦亚胺与4-甲苯基异氰酸酯、对甲硫苯酚的串联aza-Wittig反应合成了2-(4-甲硫基苯氧基)-3-(4-甲苯基)-4H-咪唑啉-4-酮衍生物.探讨了反应进行的条件和产物的波谱性质,提出了可能的环化反应机理.生成的环化产物均为新的化合物,其结构经元素分析、IR、1H NMR和MS确证.并探讨了所合成的新型杂环化合物的生物活性,结果表明部分化合物表现出良好的抑菌活性,其中3f的活性最好,在质量分数为5×10-5浓度时,对稻瘟菌和苹果轮纹菌的抑制率均达到100%.