Negishi Coupling for Highly Selective Syntheses of Allenes via Ligand Effect and Mechanistic Study via SAESI-MS/MS  

作　　者：Yangguangyan Zheng Bukeyan Miao Anni Qin Junzhe Xiao Qi Liu Gen Li Li Zhang Fang Zhang Yinlong Guo Shengming Ma 

机构地区：[1]Department of Chemistry,Fudan University,220 Handan Lu,Shanghai 200433,China [2]State Key Laboratory of Organometallic Chemistry,Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences,345 Lingling Lu,Shanghai 200032,China [3]National Center for Organic Mass Spectrometry in Shanghai,Shanghai Institute of Organic Chemistry,Chinese Academy of Sciences,345 Lingling Lu,Shanghai 200032,China

出　　处：《Chinese Journal of Chemistry》2019年第10期1003-1008,共6页中国化学（英文版）

基　　金：Financial supports from the National Natural Science Foundation of China(Grant No.21690063);the National Basic Re1search Program(2015CB856600)are greatly appreciated.

摘　　要：β-H elimination is an intrinsic problem in transition metal-catalyzed reactions.We describe herein an interesting ligand effect for Et2Zn acting as either ethyl provider or H provider,respectively:by applying SPhos or Gorlos-Phos as the ligand,β-H elimination has been successfully controlled in the corresponding Negishi coupling reaction affording different poly-substituted allenes in good yields and excellent selectivities.SAESI-MS (Solvent Assisted Electrospray Ionization Mass Spectrometry) has been applied to successfully capture the highly reactive organometallic intermediates,which show the different coordination behaviors of Pd with SPhos or Gorlos-Phos as the ligand in the catalytic cycle.In addition,the different reactivities of Int 1 and Int 2 towards the formation of the final allene products have been demonstrated via SAESI-MS/MS experiments.These MS studies visualized the whole catalytic cycle for the Negishi coupling reaction while nicely explain the observed reactivity and selectivity.

关 键 词：elimination HIGHLY SUBSTITUTED 

分 类 号：O62[理学—有机化学]