Similarity and Differences in the Regioselectivities of Thermal and Acid-Catalyzed van Alphen–Hüttel Rearrangements in the Series of 3,3-Diphenyl-3H-pyrazoles Containing Electron-Withdrawing Substituents on C4 and C5
作者:V. A. Vasin、V. V. Razin、E. V. Bezrukova
DOI:10.1134/s1070428018070138
日期:2018.7
Alphen–Hüttel rearrangement with migration of one phenyl group to C4 on heating in an aprotic solvent (benzene, toluene), as well as on keeping at 20°C in acetic acid in the presence of a catalytic amount of concentrated sulfuric acid. Under similar conditions, 3,3-diphenyl-3H-pyrazoles with a strong electronwithdrawing group (sulfo or cyano) on C4 isomerize to 1H-pyrazoles viamigration of one phenyl group to
Silver-catalyzed decarboxylative cyclization for the synthesis of substituted pyrazoles from 1,2-diaza-1,3-dienes and α-keto acids
作者:Sarita Katiyar、Abhishek Kumar、Koneni V. Sashidhara
DOI:10.1039/d2cc01793h
日期:——
A silver-catalyzed decarboxylative cyclization process has been developed for the synthesis of substituted pyrazoles from the readily available 1,2-diaza-1,3-dienes and α-keto acids. Under the optimized conditions, a series of multisubstituted pyrazoles were well prepared in moderate to good yields. In addition, the synthetic utility of this protocol has been demonstrated by synthesizing analogs of
已经开发了一种银催化的脱羧环化方法,用于从容易获得的 1,2-二氮杂-1,3-二烯和 α-酮酸合成取代的吡唑。在优化的条件下,一系列多取代吡唑以中等至良好的收率很好地制备。此外,该协议的合成效用已通过合成 FDA 批准的药物(如抗炎药、lonazolac 和抗肥胖药物 rimonabant)的类似物得到证明。
Hassaneen, Hamdi M.; Hilal, Rifaat H.; Elwan, Nehal M., Journal of Heterocyclic Chemistry, 1984, vol. 21, p. 1013 - 1016
作者:Hassaneen, Hamdi M.、Hilal, Rifaat H.、Elwan, Nehal M.、Harhash, Abdelhamid、Shawali, Ahmad S.