Department of Biomolecular Engineering, Tokyo Institute of Technology, Box B52, Nagatsuta-cho 4259, Midori-ku, Yokohama 226-8501, Japan.
J Org Chem. 2009 Mar 6;74(5):1939-51. doi: 10.1021/jo802426g.
Allylic substitution with sp(2)-carbon reagents (aryl and alkenyl anions) was realized by using allylic picolinates and copper reagents derived from RMgBr and CuBr x Me(2)S to afford anti S(N)2' 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 compatible with alkyl reagents as well. Furthermore, the substitution was applied to construction of a quaternary center and synthesis of (-)-sesquichamaenol. Electron-withdrawing nature of the pyridyl group and chelation of the C(=O)-C(5)H(4)N to MgBr(2) generated in situ were found to be responsible for the high efficiency of the substitution.
通过使用烯丙基吡啶酸盐和 RMgBr 和 CuBr x Me(2)S 衍生的铜试剂，实现了 sp(2)-碳试剂（芳基和烯基阴离子）的烯丙基取代，从而以反式 S(N)2'产物的形式高区域和立体选择性地得到产物。试剂中的立体和电子因素以及烯丙基部分周围亚甲基取代基的大小对选择性略有影响。该反应体系也与烷基试剂相容。此外，该取代反应还被应用于构建季碳原子和合成(-)-sesquichamaenol。吡啶基的吸电子性质和原位生成的 C(=O)-C(5)H(4)N 与 MgBr(2)的螯合被认为是取代反应高效的原因。
