The Vinylogous Michael Addition of 3‐Alkylidene‐2‐oxindoles to β,γ‐Unsaturated α‐Keto Esters by Bifunctional Cinchona Alkaloids
作者:Manish K. Jaiswal、Rajesh Kumar、Sanjay Singh、Shailija Jain、Kumar Vanka、Ravi P. Singh
DOI:10.1002/ejoc.202000835
日期:2020.9.22
A highly enantioselective vinylogous Michaeladdition of 3‐alkylidene‐2‐oxindoles with β,γ‐unsaturated α‐keto esters using a bifunctional tertiary‐amine thiourea catalyst is demonstrated. The challenging Michael reaction with the β,γ‐unsaturated α‐keto esters has been accomplished due to the synchronized H‐bond guided dual activation of vinylogous nucleophile and electrophile by catalyst. The reaction
证明了使用双官能叔胺硫脲催化剂,对3-亚烷基-2-氧吲哚和β,γ-不饱和α-酮酯的高对映选择性乙烯基迈克尔加成反应。由于催化剂通过同步的H键引导对乙烯基亲核试剂和亲电试剂的双重活化,已经完成了与β,γ-不饱和α-酮酸酯的具有挑战性的迈克尔反应。该反应以高收率提供产物,同时导致优异的立体控制(高达99%ee和> 19:1 E / Z)。
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.
Reported herein is an inverse-electron-demand oxa-Diels–Alder reaction that is remotely β,γ-regioselective with β,γ-unsaturated amides and β,γ-unsaturated-α-ketoesters using a bifunctional catalyst. It can provide different kinds of dihydropyrans bearing three subsequent chiral carbon centers in good to high yield (61–99%) and with complete enantioselectivity (99 to >99% ee). Furthermore, a larger-scale