Catalytic, Asymmetric Michael Reactions of Cyclic Diketones with β,γ-Unsaturated α-Ketoesters
作者:Michael A. Calter、Jun Wang
DOI:10.1021/ol900586f
日期:2009.5.21
Newly synthesized cinchona alkaloid-derived pyrimidines function as effective asymmetric catalysts for the Michael reaction between cyclicdiketones and β,γ-unsaturated α-ketoesters. The reactions of electrophiles with either aryl or alkyl γ-substituents give 64−99% yields and 94−99% ee.
Chiral N-heterocyclic carbene-catalyzed generation of ester enolate equivalents from α,β-unsaturated aldehydes for enantioselective Diels–Alder reactions
作者:Juthanat Kaeobamrung、Marisa C. Kozlowski、Jeffrey W. Bode
DOI:10.1073/pnas.1007469107
日期:2010.11.30
The catalytic generation of chiral ester enolate equivalents from alpha,beta-unsaturated aldehydes with chiral N-hetereocyclic carbene catalysts makes possible highly enantioselective hetero-Diels-Alder reactions. The reactions proceed under simple, mild conditions with both aliphatic and aromatic substituted enals as substrates. Previous attempts to employ these starting materials as enolate precursors
Highly stereoselective construction of tetrahydroquinolines via cascade aza-Michael-Michael reaction: Formal [4+2] cycloaddition of β,γ-unsaturated α-ketoesters with 2-aminochalcones
作者:Cong Duan、Yongqi Yao、Ling Ye、Zhichuan Shi、Zhigang Zhao、Xuefeng Li
DOI:10.1016/j.tet.2018.10.053
日期:2018.12
An efficient cascade aza-Michael-Michael sequence for the preparation of tetrahydroquinolines has been established. Three contiguous stereogenic centers are created with high levels of enantioselectivities (79–99% ee) and exclusive diastereoselectivities in the presence of a bifunctional squaramide. This approach is compatible with a broad range of β,γ-unsaturated α-ketoesters and 2-aminochalcones
Highly Enantioselective Synthesis of 3,4-Dihydropyrans through a Phosphine-Catalyzed [4+2] Annulation of Allenones and β,γ-Unsaturated α-Keto Esters
作者:Weijun Yao、Xiaowei Dou、Yixin Lu
DOI:10.1021/ja5109358
日期:2015.1.14
A phosphine-catalyzed novel [4+2] annulation process was devised employing allene ketones as C2 synthons and β,γ-unsaturated α-keto esters as C4 synthons. In the presence of an L-threonine-derived bifunctional phosphine, 3,4-dihydropyrans were obtained in high yields and with virtually perfect enantioselectivities. The synthetic value of the dihydropyran motif was demonstrated by a concise preparation
Organocatalytic Asymmetric Conjugate Addition and Cascade Acyl Transfer Reaction of α-Nitroketones
作者:Rui-jiong Lu、Yun-yun Yan、Jin-jia Wang、Quan-sheng Du、Shao-zhen Nie、Ming Yan
DOI:10.1021/jo2009752
日期:2011.8.5
Organocatalytic asymmetric conjugate addition of α-nitroketones to β,γ-unsaturated α-keto esters has been developed. A pyrrolidine-based thiourea–tertiary amine was identified as the best catalyst. The reaction was found to proceed via cascade conjugate addition and acyl transfer reaction. A number of α-nitroketones and β,γ-unsaturated α-keto esters were examined in this transformation. 5-Nitro-2-