A recyclable fluorous organocatalyst for Diels–Alder reactions
作者:Qianli Chu、Wei Zhang、Dennis P. Curran
DOI:10.1016/j.tetlet.2006.10.101
日期:2006.12
Chiral fluorous imidazolidinone catalyst 2 provides consistently high enantioselectivities in Diels Alder reactions of dienes and alpha,beta-unsaturated aldehydes. The catalyst can be readily separated from the reaction products by fluorous solid-phase extraction, and recovered in excellent purity for direct reuse. (c) 2006 Elsevier Ltd. All rights reserved.
Poly(ethylene glycol)-Supported Chiral Imidazolidin-4-one: An Efficient Organic Catalyst for the Enantioselective Diels–Alder Cycloaddition
A tyrosine-derived imidazolidin-4-one was immobilized on a modified poly(ethylene glycol) and converted in situ into a soluble polymer-supported catalyst for the enantioselective Diels-Alder cycloaddition of acrolein to 1,3-cyclohexadiene (up to 92% ee) and 2,3-dimethyl-1,3-butadiene (73% ee). Catalyst recycling (up to four cycles) was accompanied by some loss of the chemical efficiency and marginal erosion of the enantioselectivity.
Chiral (acyloxy)borane (CAB): a powerful and practical catalyst for asymmetric Diels-Alder reactions