The enantioselective tandemreaction of β,γ‐unsaturated α‐ketoesters with β‐alkynyl ketones was realized by a bimetallic catalytic system of achiral AuΙΙΙ salt and chiral N,N′‐dioxide‐MgΙΙ complex. The cycloisomerization of β‐alkynyl ketone and asymmetric intermolecular [4+2] cycloaddition with β,γ‐unsaturated α‐ketoesters subsequently occurred, providing an efficient and straightforward access to
Facile synthesis of substituted diaryl sulfones <i>via</i> a [3 + 3] benzannulation strategy
作者:Xiang-zheng Tang、Lang Tong、Hua-ju Liang、Jie Liang、Yong Zou、Xue-jing Zhang、Ming Yan、Albert S. C. Chan
DOI:10.1039/c8ob00662h
日期:——
base-mediated [3 + 3] benzannulation strategy for the conversion of 1,3-bis(sulfonyl)propenes and β,γ-unsaturated α-ketoesters to diaryl sulfones has been developed. This method provides facile, metal-free and efficient access to highly substituted diaryl sulfones in good to excellent yields. In addition, the sulfonyl group could be easily removed or converted to other functional groups via an organostannane
to be effective and versatile surrogates for α,β‐unsaturated aldehydes in NHC‐catalyzedasymmetricreactions. Promoted by chiral N‐heterocyclic carbenes combined with LiCl, these easy‐to‐handle solid salts could release of CO2 and then undergo asymmetricreactions via homoenolate and α, β‐unsaturated acyl azolium intermediate. The reactions have broad substrate scopes with high enantioselectivities.
Dienamine-Mediated Inverse-Electron-Demand Hetero-Diels-Alder Reaction by Using an Enantioselective H-Bond-Directing Strategy
作者:Łukasz Albrecht、Gustav Dickmeiss、Christian F. Weise、Carles Rodríguez-Escrich、Karl Anker Jørgensen
DOI:10.1002/anie.201207122
日期:2012.12.21
Giving directions: optically active dihydropyrans bearing three contiguous stereogenic centers can be efficiently prepared by the title reaction. High stereo- and regiocontrol can be achieved by employing a bifunctional H-bond-directing aminocatalyst.