Highly Enantioselective Reactions of Cyclohexanone and<i>β</i>,<i>γ</i>-Unsaturated<i>α</i>-Keto Ester: The Tuning of Chemo-selectivities by Secondary and Primary Amine Catalysts
作者:Jianwei Wei、Wengang Guo、Xin Zhou、Xin Du、Yan Liu、Can Li
DOI:10.1002/cjoc.201400431
日期:2014.10
amphiphilic imidazole based secondary and primaryaminecatalysts were synthesized and shown to be very effective with an acid cocatalyst for the asymmetric reaction of cyclohexanone to β,γ‐unsaturated α‐keto ester. Interestingly, primary and secondaryaminecatalysts show different regio‐selectivities in this reaction. Under the catalysis of secondaryamine 1, excellent enantioselectivities were observed for
Synthesis of optically active dihydropyrans from asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-ketoesters with allenic esters
作者:Cheng-Kui Pei、Yu Jiang、Min Shi
DOI:10.1039/c2ob25475a
日期:——
β-Isocupreidine (β-ICD) catalyzed asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-ketoesters with allenicesters afforded ester-substituted functionalizeddihydropyran derivatives in high yields along with high enantioselectivities under mild conditions.
A Facile Approach to Optically Active Hydroquinoline-2-carboxylates by a One-Pot Asymmetric Michael/Transamination/Cyclization Process
作者:Chao Rong、Hongjie Pan、Mao Liu、Hua Tian、Yian Shi
DOI:10.1002/chem.201503327
日期:2016.2.24
An efficient one‐potsynthesis of optically active hydroquinoline‐2‐carboxylates from 1,3‐cyclohexanediones, β,γ‐unsaturated α‐keto ester, and benzylamine in the presence of a chiral base catalyst and 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) with good diastereoselectivity and high enantioselectivity is described. The reaction proceeds by a sequential asymmetric Michael/transamination/cyclization process