Borane‐Catalyzed Chemoselective and Enantioselective Reduction of 2‐Vinyl‐Substituted Pyridines
作者:Jun‐Jie Tian、Zhao‐Ying Yang、Xin‐Shen Liang、Ning Liu、Chen‐Yu Hu、Xian‐Shuang Tu、Xiang Li、Xiao‐Chen Wang
DOI:10.1002/anie.202007352
日期:2020.10.12
Herein, we report that highly chemoselective and enantioselectivereduction of 2‐vinyl‐substituted pyridines has been achieved for the first time. The reaction, which uses chiral spiro‐bicyclic bisboranes as catalysts and HBpin and an acidic amide as reducing reagents, proceeds through a cascade process involving 1,4‐hydroboration followed by transfer hydrogenation of a dihydropyridine intermediate
Spiro‐Bicyclic Bisborane Catalysts for Metal‐Free Chemoselective and Enantioselective Hydrogenation of Quinolines
作者:Xiang Li、Jun‐Jie Tian、Ning Liu、Xian‐Shuang Tu、Ning‐Ning Zeng、Xiao‐Chen Wang
DOI:10.1002/anie.201900907
日期:2019.3.26
A new series of spiro‐bicyclic bisborane catalysts has been prepared by means of hydroboration reactions of C2‐symmetric spiro‐bicyclic dienes with HB(C6F5)2 and HB(p‐C6F4H)2. When used for hydrogenation of quinolines, these catalysts give excellent yields and enantiomeric excesses, and show turnover numbers of up to 460. The most attractive feature of these metal‐free hydrogenation reactions was the
通过C 2对称螺双环二烯与HB(C 6 F 5)2和HB(p C 6 F 4 H)2的硼氢化反应制备了一系列新的螺双环双硼烷催化剂。当用于喹啉加氢时,这些催化剂具有出色的收率和对映体过量,并且显示出高达460的周转率。这些无金属加氢反应的最吸引人的特点是宽泛的官能团耐受性,使该方法可与现有方法互补喹啉加氢的方法。
Borane-Catalyzed Direct Asymmetric Vinylogous Mannich Reactions of Acyclic α,β-Unsaturated Ketones
作者:Jun-Jie Tian、Ning Liu、Qi-Fei Liu、Wei Sun、Xiao-Chen Wang
DOI:10.1021/jacs.1c00006
日期:2021.3.3
Herein, we report that, by using chiral bicyclic bisborane catalysts, we have achieved the first highly regio-, diastereo-, and enantioselective direct asymmetric vinylogous Mannich reactions of acyclic α,β-unsaturatedketones. The strong Lewis acidity and steric bulk of the bisborane catalysts were essential for the observed high yields and selectivities.
Bifunctional Borane Catalysis of a Hydride Transfer/Enantioselective [2+2] Cycloaddition Cascade
作者:Ming Zhang、Xiao‐Chen Wang
DOI:10.1002/anie.202106168
日期:2021.7.26
Herein, we present a mild and efficient method for synthesizing enantioenriched tetrahydroquinoline-fused cyclobutenes through a cascade reaction between 1,2-dihydroquinolines and alkynones with catalysis by chiral spiro-bicyclic bisboranes. The bisboranes served two functions: first they catalyzed a hydride transfer to convert the 1,2-dihydroquinoline substrate to a 1,4-dihydroquinoline, and then