New General Method for Regio- and Stereoselective Allylic Substitution with Aryl and Alkenyl Coppers Derived from Grignard Reagents

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• 作者：Yohei Kiyotsuka ; Yuji Katayama ; Hukum P. Acharya ; Tomonori Hyodo ; Yuichi Kobayashi*
• 刊名：Journal of Organic Chemistry
• 出版年：2009
• 出版时间：March 6, 2009
• 年：2009
• 卷：74
• 期：5
• 页码：1939-1951
• 全文大小：433K
• 年卷期：v.74,no.5(March 6, 2009)
• ISSN：1520-6904

文摘

Allylic substitution with spp>2p>-carbon reagents (aryl and alkenyl anions) was realized by using allylic picolinates and copper reagents derived from RMgBr and CuBr·Me₂S to afford anti S_N2′ 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)-C₅H₄N to MgBr₂ generated in situ were found to be responsible for the high efficiency of the substitution.