Diastereo- and Enantioselective Tandem Michael Addition and Lactonization Catalyzed by Chiral Quaternary Ammonium Phenoxide: Stereoselective Synthesis of the Two Enantiomers by Using a Single Chiral Source
Diastereo- and enantio-selective synthesis of 3,4-dihydropyran-2-ones from various silyl enolates and α,β-unsaturated ketones were successfully carried out by using cinchonidine-derived quaternary ammonium phenoxide. In this reaction, a synthesis of the two enantiomers was achieved by an appropriate choice of a substituent on the bridgehead nitrogen of cinchonidine.
Polyhalides as Efficient and Mild Oxidants for Oxidative Carbene Organocatalysis by Radical Processes
作者:Xingxing Wu、Yuexia Zhang、Yuhuang Wang、Jie Ke、Martin Jeret、Rambabu N. Reddi、Song Yang、Bao-An Song、Yonggui Robin Chi
DOI:10.1002/anie.201611692
日期:2017.3.6
Simple and inexpensive polyhalides (CCl4 and C2Cl6) have been found to be effective and versatile oxidants in removing electrons from Breslow intermediates under N‐heterocyclic carbene (NHC) catalysis. This oxidative reaction involves multiple single‐electron‐transfer (SET) processes and several radical intermediates. The α, β, and γ‐carbon atoms of aldehydes and enals could be readily functionalized
1,2- vs 1,4-Addition of Acylbenzotriazoles to α,β-Unsaturated Aldehydes and Ketones. A Novel Route to 3-Alkyl-4,6-diaryl-3,4-dihydropyran-2-ones
作者:Alan R. Katritzky、Olga V. Denisko
DOI:10.1021/jo011082s
日期:2002.5.1
Lithiation of aliphatic 1-acylbenzotriazoles with subsequent reaction with alpha,beta-unsaturated ketones and aldehydes affords either 3,4,6-trisubstituted 3,4-dihydropyran-2-ones or 1,3-dienes depending on the carbonyl reagent used. Substituent effects on product yield and isomer ratio are discussed.