Polystyrene-supported cu(II)-R-Box as recyclable catalyst in asymmetric Friedel–Crafts reaction
作者:V. G. Desyatkin、M. V. Anokhin、V. O. Rodionov、I. P. Beletskaya
DOI:10.1134/s1070428016120010
日期:2016.12
complex of copper(II) trifluoromethanesulfonate with chiral isopropyl bis(oxazoline) ligand (i-Pr-Box) was immobilized on accessible and inexpensive Merrifield resin according to a “click” procedure. The resulting catalyst showed high efficiency and recyclability in the asymmetricFriedel–Craftsalkylation of indole and its derivatives. The catalyst can be recycled five times without appreciable loss in
A highly efficient enantioselective Friedel-Crafts alkylation of indoles with alkylidene malonates has been developed using chiral N,N'-dioxide LA-scandium(III) complex as the catalyst, giving the corresponding products in high yields with excellent enantioselectivities (up to 99% yield and 95% ee). The product 3a was facilely converted into several interesting compounds, such as tryptamines, indolepropionic acids and beta-carbolines. It is noteworthy that the seven-membered beta-carboline-like compound has been synthesized for the first time. Based on the crystal structure of the chiral N,N'-dioxide L10-scandium(III) complex, the proposed transition state and possible catalytic cycle were presented to elucidate the reaction mechanism. (C) 2009 Elsevier Ltd. All rights reserved.