协同亲核取代,称为 S N 2 反应,是合成中用于引入新官能团并构建碳-碳和碳-杂原子键1 的基本有机转化。 S N 2 反应通常涉及亲核试剂对C( sp 3 )−X 键(X=卤素或其他离去基团)的σ* 轨道的背面攻击,导致立体中心2的完全反转。相比之下,电子无偏sp 2乙烯基亲电子试剂上相应的立体反转亲核取代,即协同 S N V(σ) 反应,要罕见得多,并且到目前为止,仅限于精心设计的底物,主要发生在成环过程中3,4 。在这里,我们表明,金属化配合物中提出的应变释放机制可以加速协同的 S N V 反应,从而导致多种有机硼酸酯的通用和立体特异性亚烯基同系物的发展。该方法能够迭代并入多个亚烯基单元,从而产生以其他方式难以制备的交叉共轭多烯。还证明了其在含有多取代烯烃的生物活性化合物的合成中的进一步应用。计算研究表明,方形平面过渡态中空间应变的减少促进了一种不寻常的 S N 2 样协同途径,这解释了这种金属化物
Iron-Based Catalyst for Borylation of Unactivated Alkyl Halides without Using Highly Basic Organometallic Reagents
作者:Sheema Siddiqui、Ramesh Bhawar、K. Geetharani
DOI:10.1021/acs.joc.0c02364
日期:2021.1.15
alkyl bromides and chlorides with bis(neopentylglycolato)diborane (B2neop2) mediated by iron-bis amide is described. The reaction proceeds with a broad substrate scope and good functional group compatibility. Moreover, sufficient catalytic activity was obtained for primary and secondary alkyl halides. Mechanistic studies indicate that the reaction proceeds through a radical pathway.
Copper-catalyzed Borylation of Primary and Secondary Alkyl Halides with Bis(neopentyl glycolate) Diboron at Room Temperature
作者:Xin Lou、Zhen-Qi Zhang、Jing-Hui Liu、Xiao-Yu Lu
DOI:10.1246/cl.150881
日期:2016.2.5
Borylation reactions are heavily dependent on diboron agents, whose structures prescribe the reaction conditions. It necessitates extended investigation of borylation reactions using other diboron ...
Base‐Mediated Radical Borylation of Alkyl Sulfones
作者:Mingming Huang、Jiefeng Hu、Ivo Krummenacher、Alexandra Friedrich、Holger Braunschweig、Stephen A. Westcott、Udo Radius、Todd B. Marder
DOI:10.1002/chem.202103866
日期:2022.1.13
The utilization of inactivated alkyl sulfones as alkylradical precursors in a base-mediated borylation reaction with B2neop2 is reported, allowing direct access to valuable alkyl boronate esters without further transesterification. This approach is scalable and is tolerant to a variety of functional groups and substrates including complex molecules.
据报道,在与 B 2 neop 2的碱介导的硼基化反应中,利用失活的烷基砜作为烷基自由基前体,从而无需进一步酯交换即可直接获得有价值的烷基硼酸酯。这种方法具有可扩展性,并且能够耐受各种官能团和底物,包括复杂分子。
1,<i>n</i>-Bisborylalkanes via Radical Boron Migration
perfluoroalkyl radical addition. It is shown that radical 1,2- and 1,4-boron migrations to provide geminal and 1,3-bisborylalkanes are efficient transformations. The 1,5-boron migration in the homologous series leading to 1,4-bisborylalkanes is also occurring, albeit with lower efficiency. Experimental results are supported by DFT calculations which also reveal the corresponding 1,3-boron migration in such
Zinc-Catalyzed Borylation of Primary, Secondary and Tertiary Alkyl Halides with Alkoxy Diboron Reagents at Room Temperature
作者:Shubhankar Kumar Bose、Katharina Fucke、Lei Liu、Patrick G. Steel、Todd B. Marder
DOI:10.1002/anie.201308855
日期:2014.2.10
A new catalytic system based on a ZnII NHC precursor has been developed for the cross‐coupling reaction of alkyl halides with diboron reagents, which represents a novel use of a Group XII catalyst for CX borylation. This approach gives borylations of unactivated primary, secondary, and tertiary alkyl halides at room temperature to furnish alkyl boronates, with good functional‐group compatibility,