Highly enantioselective 1,4-addition of arylzinc reagents to 3-arylpropenals catalyzed by a rhodium–binap complex in the presence of chlorotrimethylsilane
摘要:
Asymmetric 1,4-addition of arylzinc chlorides to (E)-3-arylpropenals proceeded with high enantioselectivity in the presence of a rhodium/(R)-binap catalyst and chlorotrimethylsilane to give, after hydrolysis, high yields of the corresponding 3.3-diarylpropanals of 98-99% ee. The presence of the chlorosilane is essential for high yields of the 1,4-addition products. (c) 2006 Elsevier Ltd. All rights reserved.
Asymmetric 1,4-addition of arylboronic acids to α,β-unsaturated aldehydes proceeded in the presence of a rhodium catalyst (3 mol %) coordinated with a chiral diene ligand ((R,R)-Bn-bod*) to give the corresponding β-arylaldehydes with perfect 1,4-selectivity and with 88–97% enantioselectivity.
New C2-symmetric chiral diene ligands bearing a tetrafluorobenzobarrelene framework and (−)-menthylgroups as chiralauxiliaries were prepared through [4 + 2] cycloaddition of 1,4-bis((−)-menthoxym...
chiral Rh and Rh/Ag bimetallic nanoparticle catalysts consisting of polystyrene-based polymers with chiral diene moieties. The catalysts enable high-to-excellent yields and enantioselectivities to be obtained in asymmetric 1,4-addition reactions of arylboronic acids with α,β-unsaturated carbonyl compounds such as ketones, esters, and amides, and in other asymmetric reactions. The catalysts could be readily
Palladium and a simple chiral amine are used as co‐catalysts for the enantioselective conjugate addition of aryl boronic acids to α,β‐unsaturated aldehydes (see scheme). The synthetic utility of this co‐catalyzed reaction was demonstrated in the short total syntheses of (R)‐(−)‐curcumene and 4‐aryl‐2‐ones.
Chiral dihydrobenzo[1,4]oxazines as catalysts for the asymmetric transfer-hydrogenation of α,β-unsaturated aldehydes
作者:Christian Ebner、Andreas Pfaltz
DOI:10.1016/j.tet.2011.10.051
日期:2011.12
A new class of organocatalysts based on the structure of 2,3-dihydrobenzo[1,4]oxazine was prepared and applied in the enantioselective transfer-hydrogenation of α,β-unsaturatedaldehydes with Hantzsch ester as hydride donor. These catalysts proved to be particularly effective for the conjugate reduction of β,β-diaryl-substituted acrylaldehydes leading to saturated aldehydes bearing a stereogenic center