Direct access to 1,4-disubstituted 1,2,3-triazoles through organocatalytic 1,3-dipolar cycloaddition reaction of α,β-unsaturated esters with azides
作者:Wenjun Li、Xiao Zhou、Yepeng Luan、Jian Wang
DOI:10.1039/c5ra19038j
日期:——
DBU-catalyzed organocatalytic 1,3-dipolarcycloadditionreactions of α,β-unsaturated esters with azides have been developed. This strategy generates 1,4-disubstituted 1,2,3-triazoles in high yields with high regioselectivities. It is demonstrated that some of these products can be transformed into important pharmaceutical agents.
Isatogenols as Precursors for the Synthesis of Fully Substituted Indolines through Regio- and Stereoselective [3 + 2] Cycloaddition Using Various Olefins
isatogen derivatives bearing a hydroxy group at the C3-position (isatogenol) and their synthetic application to highly regio- and stereoselective [3 + 2] cycloaddition reactions. This method provides facile access to polyfused and highly functionalized heterocycles including consecutive stereocenters. Furthermore, DFT calculations revealed that hydrogen bonding is a key to controlling the regio- and stereoselectivity
Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups in supercritical carbon dioxide: selective control and mechanism
作者:Zhao-Yang Wang、Huan-Feng Jiang、Xiao-Yue Ouyang、Chao-Rong Qi、Shao-Rong Yang
DOI:10.1016/j.tet.2006.08.041
日期:2006.10
Pd(II)-catalyzed acetalization of terminal olefins with electron-withdrawing groups was carried out smoothly in supercritical carbon dioxide under oxygen atmosphere when polystyrene-supported benzoquinone (PS-BQ) or Cu-II (Cu-I) chloride was employed as cocatalyst. The higher selectivity was achieved, without any chlorinated by-product detected, when using PS-BQ instead of Cu-II (or Cu-I) chloride. PS-BQ could be recycled with excellent catalytic activity remaining after each simple filtration. Chlorine ion was demonstrated to be a promoter. The different acetalization mechanisms were revealed by the subtle relationship of chlorine ion and benzoquinone (BQ) to the catalytic activity of PdCl2/PS-BQ, Pd-II-CUCl2 or Pd(OAc)(2)/PS-BQ. (c) 2006 Elsevier Ltd. All rights reserved.