Photoredox‐Catalyzed Functionalization of Alkenes with Thiourea Dioxide: Construction of Alkyl Sulfones or Sulfonamides
作者:Yuewen Li、Jin‐Biao Liu、Fu‐Sheng He、Jie Wu
DOI:10.1002/cjoc.201900505
日期:2020.4
functionalization of alkenes with thiourea dioxide under visible‐light irradiation is achieved. The reaction of alkenes, thiourea dioxide and electrophiles provides a green and efficient access to alkylsulfones and sulfonamides. A broad reaction scope is presented with good functional group compatibility and excellent regioselectivity. A plausible mechanism involving a radical addition process with sulfur
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
waxy or even insoluble stilbazoles. Moreover, the oxalicacid loading could be lowered to sub-stoichiometric amounts. When further optimizations were needed, our strategy was found to be highly flexible to identify other oligocarboxylic acids as alternative additive to improve or even overturn regioselectivity. Oxalicacid and other oligocarboxylic acids were found to be capable of orienting more than