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.
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
Asymmetric addition of arylboroxines to δ-aryl-α,β,γ,δ-unsaturated ketones proceeded in the presence of an iridium catalyst coordinated with a chiral diene ligand to give high yields of δ-diaryl ketones with very high enantioselectivity.