1,1-Carboboration of 1-Alkynes: A Conceptual Alternative to the Hydroboration Reaction
摘要:
Strongly electrophilic boranes R-B(C6F5)(2) react readily with a variety of 1-alkynes by means of a 1,1-carboboration reaction to yield alkenylborane products, which can subsequently be used as reagents in metal catalyzed cross-coupling reactions.
通过1,1-碳链化路线制备了一系列烯基硼烷,并将其用作路易斯酸组分,用于产生沮丧的路易斯对(FLP)。1-炔烃与B(C 6 F 5)3的反应得到RCH═C(C 6 F 5)B(C 6 F 5)2系统4a(R = n -C 3 H 7),4b(R = n -C 4 H 9),4c(R = Ph)和4d(R = t -C 4 H 9), 分别。在环境温度下,衍生自化合物4a – d的烯基硼烷/ t Bu 3 P FLP与二氢(2.5 bar)迅速反应。笨重的系统4D离开alkenylborane不饱和的C = C双键和,得到二氢裂解产物[吨卜3 PH] [吨BuCH═C(C 6 ˚F 5)BH(C 6 ˚F 5)2 ](10D) 。相比之下,体积较小的系统4a / t, Bu 3 P和4b / t在这些条件下,Bu 3 P分解成二氢,并干净地还原了它们的C═C双键,生成了相应的1-五氟苯基烷基氢硼酸盐[
Stoichiometric and catalytic isomerization of alkenylboranes using bulky Lewis bases
作者:Fu An Tsao、Anson Sathaseevan、Hui Zhu、Stefan Grimme、Gerhard Erker、Douglas W. Stephan
DOI:10.1039/c7cc04904h
日期:——
isomers of RCH = CR′B(C6F5)2 (R = (CH2)2Me, (CH2)3Me, (CH2)2Ph, CH2CHMe2, CHMe2, CMe3, CH2OMe, CH2N(CO)2C6H4), treatment of these alkenylboranes with stoichiometric or catalytic amounts of tBu2PH or other donors are shown to induce isomerization. The proposed mechanism involving a zwitterionic borataalkene intermediate is supported by computations.
与硼烷R'B炔烃的1,1- Carboboration(C 6 ˚F 5)2(R'=(CH 2)3博士,C 6 ˚F 5)所述的,得到的混合物Ë和Ž RCH = CR'B的异构体( C 6 F 5)2(R =(CH 2)2 Me,(CH 2)3 Me,(CH 2)2 Ph,CH 2 CHMe 2,CHMe 2,CMe 3,CH 2 OMe,CH 2 N(CO) )在2 C 6 H 4)中,显示出用化学计量或催化量的t Bu 2 PH或其他供体处理这些烯基硼烷会诱导异构化。计算结果支持了所提出的涉及两性离子硼烷基烯烃中间体的机理。
Exploring the Limits of Frustrated Lewis Pair Chemistry with Alkynes: Detection of a System that Favors 1,1-Carboboration over Cooperative 1,2-P/B-Addition
[(C6F5)2B‐(CH2)3‐Cp}(Cp‐PtBu2)ZrCl2] (6; Cp=cyclo‐C5H4) was prepared by hydroboration of [(allyl‐Cp)(Cp‐PtBu2)ZrCl2] (5) with HB(C6F5)2 (“Piers’ borane”). It represents a frustratedLewispair (FLP) in which both the Lewis acid and the Lewis base were attached at the metallocene framework. Its reaction with 1‐pentyne did not result in the 1,2‐addition of or deprotonation reaction by the FLP, but rather in
锆茂复合物[(C 6 F 5)2 B-(CH 2)3 -Cp}(Cp-P t Bu 2)ZrCl 2 ](6 ; Cp = cyclo-C 5 H 4)是通过对[(烯丙基-Cp)(Cp-P t Bu 2)ZrCl 2 ](5)与HB(C 6 F 5)2(“ Piers'borane”)。它代表沮丧的路易斯对(FLP),其中路易斯酸和路易斯碱都连接在茂金属骨架上。它与1-戊炔的反应不会导致FLP的1,2-加成或去质子反应,而是三键的1,1-碳环化,从而获得Z / E混合物(1.2:1)各自的有机金属取代的烯烃7。1-戊炔与无磷体系[(C 6 F 5)2 B-(CH 2)3 -Cp)} CpZrCl 2 [ 9 ]的类似反应给出了各自的1,1-碳化产物(Z ‐10/ E- 10≈1.3:1)。
6-Dimethylaminopentafulvene as a Lewis Base Component in Frustrated Lewis Pairs: Reversible Carbon–Carbon Coupling in FLP Chemistry
The strongly electrophilic boranes RB(C6F5)(2) form frustrated Lewis pairs with an aminofulvene derivative. The new C/B FLPs undergo typical cooperative 1,2-addition reactions to alkynes with carbon-carbon bond formation.
1,1-Carboboration of 1-Alkynes: A Conceptual Alternative to the Hydroboration Reaction
Strongly electrophilic boranes R-B(C6F5)(2) react readily with a variety of 1-alkynes by means of a 1,1-carboboration reaction to yield alkenylborane products, which can subsequently be used as reagents in metal catalyzed cross-coupling reactions.
Alkenylborane-Derived Frustrated Lewis Pairs: Metal-Free Catalytic Hydrogenation Reactions of Electron-Deficient Alkenes
作者:J. Sreedhar Reddy、Bao-Hua Xu、Tayseer Mahdi、Roland Fröhlich、Gerald Kehr、Douglas W. Stephan、Gerhard Erker
DOI:10.1021/om3006068
日期:2012.8.13
these alkenylboranes undergo FLP reactions acting as catalysts for the hydrogenation of imines. Perhaps most remarkably, some of these alkenylboranes retain the C═C double bonds under FLP/H2 reaction conditions and heterolytically split dihydrogen in the presence of the Lewis base DABCO and catalyze the hydrogenation of the electron-poor C═C double bonds of diaryl-substituted enones.
通过1,1-碳链化路线制备了一系列烯基硼烷,并将其用作路易斯酸组分,用于产生沮丧的路易斯对(FLP)。1-炔烃与B(C 6 F 5)3的反应得到RCH═C(C 6 F 5)B(C 6 F 5)2系统4a(R = n -C 3 H 7),4b(R = n -C 4 H 9),4c(R = Ph)和4d(R = t -C 4 H 9), 分别。在环境温度下,衍生自化合物4a – d的烯基硼烷/ t Bu 3 P FLP与二氢(2.5 bar)迅速反应。笨重的系统4D离开alkenylborane不饱和的C = C双键和,得到二氢裂解产物[吨卜3 PH] [吨BuCH═C(C 6 ˚F 5)BH(C 6 ˚F 5)2 ](10D) 。相比之下,体积较小的系统4a / t, Bu 3 P和4b / t在这些条件下,Bu 3 P分解成二氢,并干净地还原了它们的C═C双键,生成了相应的1-五氟苯基烷基氢硼酸盐[