Facile one-pot synthesis of 5-substituted isoxazoles and pyrazoles through microwave-promoted intramolecular cyclization of <font>γ</font>-hydroxyalkynal oximes and hydrazones
作者:Denis A. Bulanov、Irina A. Novokshonova、Vladimir V. Novokshonov、Igor A. Ushakov、Irina V. Sterkhova
DOI:10.1080/00397911.2016.1263892
日期:2017.2.16
ABSTRACT Simple and efficient one-pot synthesis of 5-substituted isoxazoles and pyrazoles has been developed. The formation of the target isoxazoles and pyrazoles is initiated by 1,2-nucleophilic addition of generated in situ hydroxylamine or hydrazine to α-acetylenic γ-hydroxyaldehydes with further intramolecular cyclization of the adducts. The protocols are associated with readily available substrates
addition of methyl diazoacetate (I) to the carbonyl group of the substituted propyn-1-als RCCCHO (II) (R = alkyl, Alk3Si, Et3Ge) to give the corresponding methyl esters of 2-diazo-3-hydroxy-4-pentyn carboxylic acid RCCCH(OH)C(N2)COOMe (III) have been found. Shielding of the triple bond in II by the bulky R group or complexation with dicobaltoctacarbonyl, the presence of strong electron acceptor
未催化,选择性地将重氮乙酸甲酯(I)加至取代的丙炔基1-丙二醛RCCCHO(II)(R =烷基,Alk 3 Si,Et 3 Ge)的羰基上的最佳条件已经发现2-重氮-3-羟基-4-戊炔羧酸RC = CCH(OH)C(N 2)COOMe(III)的相应甲酯。通过庞大的R基团屏蔽二代中的三键,或与二钴八羰基二钴络合,在二代的3位上存在强电子受体(4-NO 2 C 6 H 4),并且溶剂的极性低在选择性羟醛缩合中。γ-羟基丙醛R 1 R 2的反应具有重氮乙酸甲酯的C(OH)= CCHO也通过醛醇型加成而进行,并且涉及两个丙炔分子,形成二炔基重氮四环(VIII)。将重氮乙酸甲酯的β加成到三烷基甲硅烷基或-锗基丙炔中的三键上,得到异构的甲酰基吡唑IV和V.IV的4位上含Si或Ge的取代基的存在会促进它们的二聚为三环半胱氨酸,VI。
Synthesis of 4-Alkynyl-substituted 3,4-Dihydropyrimidin-2(1<i>H</i>)-ones
作者:Vladimir V. Novokshonov、Irina A. Novokshonova、Hien T. T. Nguyen、Alevtina S. Medvedeva
DOI:10.1080/00397911.2011.556298
日期:2012.8.15
4-Alkynyl-3,4-dihydropyrimidin-2-(1H)-ones were synthesized by a one-pot reaction of propynals, ethyl acetoacetate, and urea. The yields of acetylenic dihydropyrimidinones depend significantly upon the propynal structure and catalyst type. A comparative study of the catalysts revealed an important advantage of polyphosphate ester in tetrahydrofuran in comparison with hydrochloric acid in methanol or trimethylchlorosilane in dimethylformamide, allowing the preparation of target compounds in good or moderate yields.
Synthesis of acetylenic ? -hydroxy aldehydes and their reaction with primary amines
作者:A. S. Medvedeva、L. P. Safronova、G. G. Chichkareva、M. G. Voronkov
DOI:10.1007/bf00925629
日期:1976.1
Decisive role of water in efficient noncatalyzed synthesis of polyfunctional 1H-1,2,3-triazoles proceeding from γ-hydroxypropynals
作者:A. S. Medvedeva、M. M. Demina、T. L. H. Nguyen、T. D. Vu、D. A. Bulanov、V. V. Novokshonov
DOI:10.1134/s1070428013080216
日期:2013.8
A highly efficient method was developed for the synthesis of new polyfunctional 1H-1,2,3-triazoles by the reaction of gamma-hydroxypropynals with trimethylsilyl azide in water at room temperature without catalyst. The addition of trimethylsilyl azide to gamma-hydroxypropynals occurs regioselectively: Previously unknown hydroxyalkyl-1H-1,2,3-triazolecarbaldehydes have been isolated in 69-96% yields with the prevalence of 1,5-isomers and the content of minor 1,4-isomers equal 9-21%. In the reaction of gamma-hydroxypropynals with sodium azide in DMSO the formation of 4-hydroxyalkyl-1H-1,2,3-triazole-5-carbaldehydes is accompanied by the dimerization of initial aldehydes into the corresponding 1,3-dioxolanes.