Discovery of temperature-dependent, autoinductive reversal of enantioselectivity: palladium-mediated [3+3]-annulation of 4-hydroxycoumarins
作者:Shasha Wang、Junan Xiao、Jun Li、Haoyue Xiang、Chaoming Wang、Xiaoqing Chen、Rich G. Carter、Hua Yang
DOI:10.1039/c7cc01610g
日期:——
An unusual temperature-dependent autoinductive reversal of enantioselectivity (TARE) was discovered in an asymmetric palladium-mediated [3+3]-annulation of 4-hydroxycoumarin with Morita-Baylis-Hillmanacetate. The absolute stereochemistry of the reaction product can be readily...
Unusual Ligand-to-Metal-Ratio-Controlled Bidirectional Enantioselectivity in Pd-Catalysed [3+3]-Annulation of Morita-Baylis-Hillman Acetate
作者:Jun Li、Sha-Sha Wang、Peng-Ju Xia、Qing-Lan Zhao、Jun-An Xiao、Hao-Yue Xiang、Xiao-Qing Chen、Hua Yang
DOI:10.1002/ejoc.201701315
日期:2017.12.15
An unusual ligand-to-palladium-ratio-dependent reversal of enantioselectivity was systematically observed in the asymmetric Pd-catalysed [3+3]-annulation of Morita-Baylis-Hillmanacetate with 4-hydroxycoumarin or 1,3-cyclohexanedione. The absolute configurations of the annulation products can be readily inversed by simply modifying L/Pd ratio from 1:3 to 2:1.
The Friedel-Crafts reaction of a wide variety of arenes and heteroarenes was accomplished, in good to excellent yields (50-98%) and with high alpha -regioselectivity, using Morita-Baylis-Hillman acetates. Functionalized conjugated enones were obtained under Bi(OTf)(3) catalysis (10 mol%) in dichloroethane (DCE) at 50 degrees C. (C) 2020 Elsevier Ltd. All rights reserved.