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
bisphenols thus prepared with dihalides afforded polyethers containing chiral imidazolidinone repeating units. These chiral imidazolidinone polyethers exhibited excellent catalytic activity in the asymmetric Diels–Alder reaction. With the use of these polymeric catalysts, enantioselectivities up to 99% were obtained, higher than those obtained by the corresponding monomeric imidazolidinone catalyst in