Tertiary Amine Mediated Tandem Cross-Rauhut-Currier/Acetalization Reactions: Access to Functionalized Spiro-3,4-Dihydropyrans
作者:Weijun Yao、Yihua Wu、Gang Wang、Yiping Zhang、Cheng Ma
DOI:10.1002/anie.200905091
日期:2009.12.14
γ‐Proton transfer furnished the highly selective title reaction in which cyclic β‐haloenals 1 react with β,γ‐unsaturated α‐ketoesters 2 to generate functionalized spiro‐3,4‐dihydro‐2H‐pyrans 3 having an α‐quaternary carbon center and an adjacent vinyl halide group in skeleton. DBU=1,8‐diazabicyclo[5.4.0]undec‐7‐ene, Tos=4‐toluenesulfonyl.
Organocatalytic asymmetric Michael-type reaction between β,γ-unsaturated α-keto ester and α-nitro ketone
作者:Pengfei Li、Sau Hing Chan、Albert S. C. Chan、Fuk Yee Kwong
DOI:10.1039/c1ob06191g
日期:——
A Michael-type reaction of β,γ-unsaturated α-keto ester and α-nitroketone was established. With a thiourea catalyst derived from cinchona alkaloid, the reactions afford products in 47–94% yields with 68–96% ee.
Highly Enantioselective Friedel-Crafts Reaction of 4,7-Dihydroindoles with β,γ-Unsaturated α-Keto Esters by Chiral Brønsted Acids
作者:Mi Zeng、Qiang Kang、Qing-Li He、Shu-Li You
DOI:10.1002/adsc.200800523
日期:2008.10.6
A highly efficient Friedel–Craftsreaction of 4,7-dihydroindoles with β,γ-unsaturatedα-ketoesters by a chiral N-triflyl phosphoramide was realized, affording the 2-substituted 4,7-dihydroindoles with up to 98% ee for a wide range of substrates. The Friedel–Crafts alkylation together with a subsequent oxidation of the product with p-benzoquinone led to a 2-alkylated indole derivative in 98% ee.
Highly Enantioselective and Efficient Organocatalytic Aldol Reaction of Acetone and β,γ-Unsaturated α-Keto Ester
作者:Pengfei Li、Junling Zhao、Fengbo Li、Albert S. C. Chan、Fuk Yee Kwong
DOI:10.1021/ol102254q
日期:2010.12.17
An effective organocatalytic asymmetric aldol reaction of acetone to β,γ-unsaturated α-keto ester has been developed. In the presence of 5 mol % of 9-amino (9-deoxy)-epicinchona alkaloid and 10 mol % of 4-nitrobenzoic acid, the aldol adducts containing a chiral tertiary alcohol moiety were obtained in excellent yields and enantioselectivities.
We report herein the enantioselectiveCu-catalyzed conjugate addition of organometallic reagents to sensitive Michael acceptors and their application to the synthesis of relevant target molecules. This is one of the most important methodologies to form a C-C bond in an enantioselective manner. A wide range of alpha,beta-unsaturated aldehydes and beta,gamma-unsaturated-alpha-ketoesters has been successfully