Rhodium-catalyzed cascade reactions: A methylenation–hydroboration homologative process
作者:Hélène Lebel、Chehla Ladjel
DOI:10.1016/j.jorganchem.2005.03.058
日期:2005.11
A very efficient rhodium-catalyzed cascade process allowing the transformation of aldehydes and ketones into their corresponding one or two-carbon homologated alcohol products through a methylenation-hydroboration sequence is reported. Wilkinson's complex is used to catalyze both reactions in a one-pot procedure that does not require the isolation of the alkene intermediate. (c) 2005 Elsevier B.V. All rights reserved.
New General Method for Regio- and Stereoselective Allylic Substitution with Aryl and Alkenyl Coppers Derived from Grignard Reagents
作者:Yohei Kiyotsuka、Yuji Katayama、Hukum P. Acharya、Tomonori Hyodo、Yuichi Kobayashi
DOI:10.1021/jo802426g
日期:2009.3.6
Allylic substitution with sp2-carbon reagents (aryl and alkenyl anions) was realized by usingallylic picolinates and copper reagents derived from RMgBr and CuBr·Me2S to afford anti SN2′ products regio- and stereoselectively. Steric and electronic factors in the reagents and the size of the methylene substituents around the allylic moiety marginally affected the selectivity. The reaction system was
通过使用烯丙基吡啶甲酸酯和衍生自RMgBr和CuBr·Me 2 S的铜试剂实现Sp 2-碳试剂(芳基和烯基阴离子)的烯丙基取代,可以在区域和立体选择性地提供抗S N 2'产物。试剂中的立体和电子因素以及烯丙基部分周围的亚甲基取代基的大小在一定程度上影响了选择性。该反应系统也与烷基试剂相容。此外,该取代被应用于四元中心的构建和(-)-倍半茶烯酚的合成。吸电子的C的吡啶基的性质和螯合(═ ö)-C 5 H ^ 4 Ñ到MgBr 2 发现原位产生的碳负责替代的高效率。