The Sulfinyl Group as a Remote Chiral Auxiliary in Stereoselective Conjugate Additions of Alkyl Groups to α-Methylidene Carbonyl Compounds Initiated by Et<sub>3</sub>B/O<sub>2</sub>
作者:José Antonio Fernández-Salas、M. Carmen Maestro、M. Mercedes Rodríguez-Fernández、José L. García Ruano
DOI:10.1002/ejoc.201201642
日期:2013.3
l] α-methylidene carbonyl compounds 1 and 2 with alkyl radicals generated from Et3B/O2 and RI give, after protonation, β-alkyl derivatives with a high degree of control of the configuration at the α carbon. In the case of aldehyde 2, when further combined with allylation of the carbonyl group, a one-pot radical-addition/protonation/allylation sequence provides a highly stereoselective synthesis of
α-[2-(对甲苯基亚磺酰基)苯基] α-亚甲基羰基化合物 1 和 2 与由 Et3B/O2 和 RI 产生的烷基反应,在质子化后得到具有高度可控构型的 β-烷基衍生物在α碳。在醛 2 的情况下,当进一步与羰基的烯丙基化结合时,一锅自由基加成/质子化/烯丙基化序列提供了具有两个相邻手性中心的化合物的高度立体选择性合成。反应的立体化学过程由作为远程手性助剂的亚磺酰基控制,该基团可以很容易地用 tBuLi 去除。