Exploring benzylic -C(sp)-boron-silicon and boron-tin centers as a synthetic platform.

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.