Chen Wei W, Fernández Nahiane Pipaon, Baranda Marta Díaz, Cunillera Anton, Rodríguez Laura G, Shafir Alexandr, Cuenca Ana B
Department of Organic and Pharmaceutical Chemistry, Institut Químic de Sarrià, URL Vía Augusta 390 Barcelona 08017 Spain
Department of Biological Chemistry, Institute of Advanced Chemistry of Catalonia, IQAC-CSIC c/ Jordi Girona 20 Barcelona 08034 Spain
Chem Sci. 2021 Jul 2;12(31):10514-10521. doi: 10.1039/d1sc01741a. eCollection 2021 Aug 11.
A stepwise build-up of multi-substituted C carbon centers is an attractive, conceptually simple, but often synthetically challenging type of disconnection. To this end, this report describes how -α,α-dimetalloid-substituted benzylic reagents bearing boron/silicon or boron/tin substituent sets are an excellent stepping stone towards diverse substitution patterns. These -dimetalloids were readily accessed, either by known carbenoid insertion into C-B bonds or by the newly developed scalable deprotonation/metallation approach. Highly chemoselective transformations of either the C-Si (or C-Sn) or the C-B bonds in the newly formed -C centers have been achieved through a set of approaches, with a particular focus on exploiting the synthetically versatile polarity reversal in organometalloids by λ-aryliodanes. Of particular note is the metal-free arylation of the C-Si (or C-Sn) bonds in such -dimetalloids the iodane-guided C-H coupling approach. DFT calculations show that this transfer of the (α-Bpin)benzyl group proceeds unusual [5,5]-sigmatropic rearrangement and is driven by the high-energy iodine(iii) center. As a complementary tool, the -dimetalloid C-B bond is shown to undergo a potent and chemoselective Suzuki-Miyaura arylation with diverse Ar-Cl, thanks to the development of the reactive -α,α-silyl/BFK building blocks.
多取代C碳中心的逐步构建是一种引人关注、概念上简单但合成上往往具有挑战性的切断方式。为此,本报告描述了带有硼/硅或硼/锡取代基的α,α - 二金属取代苄基试剂如何成为实现多种取代模式的优良垫脚石。这些二金属化合物可通过已知的类卡宾插入C - B键或新开发的可扩展去质子化/金属化方法轻松获得。通过一系列方法实现了新形成的C中心中C - Si(或C - Sn)键或C - B键的高度化学选择性转化,特别关注利用λ - 芳基碘烷在有机金属化合物中合成上通用的极性反转。特别值得注意的是此类二金属化合物中C - Si(或C - Sn)键的无金属芳基化——碘烷导向的C - H偶联方法。密度泛函理论计算表明,(α - Bpin)苄基的这种转移通过不寻常的[5,5] - 西格玛重排进行,并由高能碘(III)中心驱动。作为一种补充工具,由于反应性α,α - 硅基/BFK结构单元的开发,二金属化合物的C - B键被证明能与多种Ar - Cl发生高效且化学选择性的铃木 - 宫浦芳基化反应。