Enantioselective Synthesis of Alkyne-Substituted Quaternary Carbon Stereogenic Centers through NHC−Cu-Catalyzed Allylic Substitution Reactions with (<i>i</i>-Bu)<sub>2</sub>(Alkynyl)aluminum Reagents
作者:Jennifer A. Dabrowski、Fang Gao、Amir H. Hoveyda
DOI:10.1021/ja2010829
日期:2011.4.6
A catalytic enantioselective method for the formation of alkyne-substituted all-carbon quaternary stereogenic centers is reported. Additions of alkynylaluminums to alkyl-, aryl-, carboxylic ester-, or silyl-substituted allylic phosphates are promoted by 1.0-5.0 mol % loadings of NHC-Cu complexes derived from air-stable and commercially available CuCl(2)·2H(2)O. The requisite Al-based reagents are prepared
报道了一种用于形成炔烃取代的全碳四元立体中心的催化对映选择性方法。1.0-5.0 mol % 的 NHC-Cu 配合物可促进烷基铝向烷基、芳基、羧酸酯或甲硅烷基取代的烯丙基磷酸酯的添加)O。在环境温度下,在 5.0 mol% Et(3)N 存在下,通过用二异丁基氢化铝处理相应的芳基、杂芳基、烷基或烯基取代的末端炔烃来制备所需的基于铝的试剂。以高达 98% 的产率和 >99:1 的对映体比获得所需的 1,4-烯炔。选定的 Au 催化环化涉及对映异构体富集产品的炔烃单元作为该方法的演示