Highly effective and regioselective Michael addition of indoles to α,β-unsaturated ketones promoted by pentafluorophenylammonium triflate
作者:Samad Khaksar、Seyed Mohammad Vahdat、Fatemeh Rezaee
DOI:10.1016/j.crci.2012.08.002
日期:2013.2
Abstract A simple, inexpensive, environmentally friendly and efficient route for Michaeladdition of indoles to α,β-unsaturated ketones using pentafluorophenylammonium triflate (PFPAT) as a catalyst is described. Various indole derivatives were synthesized in good to excellent yields. The preparation of PFPAT catalyst from simple and readily available starting materials makes this method more affordable
Metal halide hydrates as lewis acid catalysts for the conjugated friedel-crafts reactions of indoles and activated olefins
作者:Cristiane S. Schwalm、Marco Antonio Ceschi、Dennis Russowsky
DOI:10.1590/s0103-50532011000400003
日期:——
CrCl2·6H2O, CoCl2·6H2O e CeCl3·7H2O were investigated as mild Lewisacidscatalysts for the conjugate Friedel-Craftsreaction between indoles and activated olefins. The reactions were carried out with aliphatic unsaturated ketones over a period of days at room temperature, while chalcones reacted only under reflux conditions. The reactions with nitrostyrenes were either performed in solvent or under
synthesis of thieno[2,3-b]indole derivatives. This method combined four C-H σ-bond cleavage reactions of two different kinds of C-H bonds and two C-S σ-bond formation processes. A series of thieno[2,3-b]indoles were obtained starting from 3-benzylindole derivatives with good yields and high regioselectivity, with the elemental sulfur serving as a cheap and readily available sulfur source. Good efficiency
The inexpensive Br2 can serve as a novel Lewis acid catalyst for Friedel–Crafts alkylation of indoles with α,β-unsaturatedketones. Under the catalysis of only 3 mol % of Br2, this Michael addition proceeded smoothly with high efficiency and broad substrate scope. Moreover, theoretical calculations suggested that Br2 possesses only the modest power to activate chalcones and is inferior to most tested
A sulfonic-acid-functionalized ionic liquid is used as a Bronsted acid catalyst for the efficientsynthesis of indolederivatives in good-to-high yields at room temperature undersolvent-free condi...