<i>C</i><sub>2</sub>-Symmetric Copper(II) Complexes as Chiral Lewis Acids. Scope and Mechanism of Catalytic Enantioselective Aldol Additions of Enolsilanes to (Benzyloxy)acetaldehyde
作者:David A. Evans、Marisa C. Kozlowski、Jerry A. Murry、Christopher S. Burgey、Kevin R. Campos、Brian T. Connell、Richard J. Staples
DOI:10.1021/ja9829822
日期:1999.2.1
C2-Symmetric bis(oxazolinyl)pyridine (pybox)−Cu(II) complexes have been shown to catalyze enantioselective Mukaiyama aldol reactions between (benzyloxy)acetaldehyde and a variety of silylketene acetals. The aldol products are generated in high yields and in 92−99% enantiomeric excess using as little as 0.5 mol % of chiral catalyst [Cu((S,S)-Ph-pybox)](SbF6)2. With substituted silylketene acetals, syn
Rare Earth Triflate-Catalyzed Addition Reactions of Acylhydrazones with Silyl Enolates. A Facile Synthesis of Pyrazolone Derivatives
作者:Hidekazu Oyamada、Shu Kobayashi
DOI:10.1055/s-1998-1638
日期:1998.3
In the presence of a catalytic amount of a rare earth triflate, benzoylhydrazones reacted with silyl enolates to afford the corresponding β-N′-benzoylhydrazino esters in high yields. The hydrazino esters thus obtained were readily converted to pyrazolone derivatives by treatment with a base. A three-component reaction between an aldehyde, an acylhydrazine, and a silyl enolate was also performed successfully.
The Stereoselective Michael Reaction of α,β-Unsaturated Thioesters with Silyl Enol Ethers Promoted by Combined Use of Antimony(V) Chloride and Tin(II) Triflate
α, β-Unsaturated thioesters react with silylenolethers to afford the corresponding Michael adducts stereoselectively in high yields by the use of a new catalyst, combined use of antimony(V) chlor...
Development of a general, enantioselective organocatalytic Mukaiyama–Michael reaction with α,β-unsaturated aldehydes
作者:Christopher J. Borths、Diane E. Carrera、David W.C. MacMillan
DOI:10.1016/j.tet.2009.06.066
日期:2009.8
LUMO-lowering organocatalysis has been extended to promote the conjugate addition of S-alkyl and 1-pyrrolyl silylketene acetals to alpha,beta-unsaturated aldehydes, yielding both, syn and anti Mukaiyama-Michael products with high levels of enantioselectivity. This strategy allows for the generation of chemically useful 1,5-dicarbonyl systems and again highlights the utility of organocatalysis. (C) 2009 Published by Elsevier Ltd.