Tetraarylphosphonium inner-salts (TAPIS) as both Lewis base catalyst and phase tag
摘要:
Tetraarylphosphonium inner-salts (TAPIS) have been designed, synthesized and verified as recyclable and reusable Lewis base catalysts. The resulted TAPIS catalyst has been successfully applied in Michael addition, cyanation and trifluoromethylation reactions. (C) 2017 Elsevier Ltd. All rights reserved.
A novel and recyclable catalyst, a C3-symmetrical cinchonine-squaramide, has been developed for the asymmetric Michaeladdition of 1,3-dicarbonylcompounds to nitroalkenes. When using only 1 mol% of catalyst 1a for the reaction, high reaction yields with excellent enantioselectivities and diastereoselectivities (up to 96% yield,>99% ee,>99:1 dr) were achieved, in which the results for cyclic keto esters
Novelbifunctionalchiralsquaramide–amine organocatalysts have been developed by rational combination of pyrrolidine and a cinchona alkaloid. The catalysts promoted the enantioselective Michael addition of both mono- and diketones to a broad range of nitroalkenes providing the corresponding products in moderate to high yields with excellent enantioselectivities and diastereoselectivities (up to 96%
motifs in organocatalysis, whereas efficient 1,3‐diamine‐derived organocatalysts are very rare. Herein we report a highly efficient camphor‐1,3‐diamine‐derived squaramideorganocatalyst. Its catalytic activity in Michaeladditions of 1,3‐dicarbonyl nucleophiles to trans‐β‐nitrostyrene derivatives provides excellent enantioselectivities (up to >99% ee).
Recyclable Chiral Bifunctional Thioureas Derived from [60]Fullerene and Their Use as Highly Efficient Organocatalysts for the Asymmetric Nitro-Michael Reaction
作者:José M. Andrés、Miguel González、Alicia Maestro、Daniel Naharro、Rafael Pedrosa
DOI:10.1002/ejoc.201601640
日期:2017.5.18
Three novel fullerothioureas derived from natural valine, phenylalanine, and tert-leucine have been prepared by Prato's reaction of [60]fullerene and the corresponding aldehydes. These hybrids have been used as organocatalysts in a typical stereoselective nitro-Michael addition reaction under homogeneous and neat conditions. The catalysts are easily recoverable by filtration, and are recyclable for
Tether-Free Immobilized Bifunctional Squaramide Organocatalysts for Batch and Flow Reactions
作者:György Kardos、Tibor Soós
DOI:10.1002/ejoc.201300626
日期:2013.7
accessible, and robust immobilizedbifunctionalorganocatalysts. There was no need to employ any tether to secure high enantio- and diastereoselectivities in various Michael addition reactions. The synthetically useful Michael adducts were obtained within reasonable reaction times with the advantage of easy product isolation and the possibility of automation by using a flow chemistry apparatus.