溶剂对钯催化的叔丁基乙炔低聚反应化学选择性的调控作用  

Solvent-Controlled Chemoselective Palladium-Catalyzed Oligomerization of tert-Butyl Acetylene

作　　者：程金生[1] 赵进[1] 黄锁义[1] 江焕峰[2] 

机构地区：[1]右江民族医学院基础医学院 [2]华南理工大学化学科学学院,广州510641

出　　处：《有机化学》2007年第5期656-662,共7页Chinese Journal of Organic Chemistry

基　　金：国家自然科学基金(No.20172053);广西壮族自治区教育厅科技基金(No.200508193);右江民族医学院科研重点基金(No.200505)资助项目.

摘　　要：报道了溶剂对钯催化的叔丁基乙炔低聚反应化学选择性的调控作用.反应可在苯-正丁醇双组分溶剂体系中顺利进行,当双组分溶剂体系中苯占优势比例时,反应发生递次的三分子炔烃顺式插入,经由顺式σ-烯钯中间体生成环三聚产物1,3,5-三叔丁基苯;而当双组分溶剂中正丁醇组分上升至一定比例,反应选择性生成(3Z,5Z)-2,2,7,7-四甲基-3,6-二氯-3,5-辛二烯或(3Z,5Z)-2,2,7,7-四甲基-3,6-二溴-3,5-辛二烯,这是由于正丁醇可显著加快C—Pdσ键的断裂,并与叔丁基乙炔、σ-烯钯中间体形成弱氢键作用力,同时也与Pd(II)和Cu(II)等离子存在配位效应.在强极性质子溶剂H2O中,反应生成偶联双炔:2,2,7,7-四甲基-3,5-辛二炔.文中就反应溶剂体系、钯铜催化剂及反应可能机理等分别进行了探讨.A novel solvent-controlled chemoselective palladium-catalyzed oligomerization of tert-butyl acetylene was reported in this paper. The reaction was carded out in benzene/n-BuOH binary solvent system smoothly. When benzene was preponderating component in the binary solvent system, a cyclotrirnefization process occurred to give 1,3,5-tri-tert-butylbenzene via a mechanism of three acetylene molecular stepwise insertions forming σ-butadienyl-Pd and σ-hexatrienyl-Pd intermediates. While when the polar, protic and strong coordinating solvent, n-BuOH, which could help to cleave the C-Pd σ-bonds and solvate Pd（Ⅱ） cation, Cu（Ⅱ） cation, halo anion and σ-butadienyl-Pd inter-mediate etc., was increased to a certain ratio in the binary solvent system, the reaction proceed readily via n-BuOH promoted mechanism to give （3Z,5Z）-2,2,7,7-tetramethyl-3,6-dichloro-3,5-octadiene or （3Z,5Z）-2,2,7,7-tetramethyl-3,6-dibromo-3,5- octadiene, respectively, instead of cyclotrimerization product. Possible weak hydrogen bonds and n-π weak force between n-BuOH and tert-butyl acetylene （or a-butadienyl-Pd intermediate） were also in favor of the n-BuOH promoted pathway. Meanwhile, a coupling product 2,2,7,7-tetramethyl-3,5-octadiyne was given exclusively when the reaction was conducted in singular polar H2O. Influences of the solvent, catalysts, and possible mechanism were discussed.

关 键 词：溶剂 叔丁基乙炔 低聚 化学选择性 钯 

分 类 号：O643.32[理学—物理化学]