Cobalt‐Catalyzed Hiyama‐Type C−H Activation with Arylsiloxanes: Versatile Access to Highly ortho‐Decorated Biaryls

Abstract

Versatile direct Hiyama‐type C−H arylations of benzamides were accomplished with organosiloxanes by chelation‐assisted cobalt catalysis. The C−H arylation featured broad substrate scope, including challenging C(sp3)−H activation, the use of γ‐valerolactone as biomass‐derived solvent, and selectively provided the desired biaryls, even when being highly sterically hindered.

Silylation of Alcohols, Phenols, and Silanols with Alkynylsilanes – an Efficient Route to Silyl Ethers and Unsymmetrical Siloxanes

“…[5] Moreover, alkoxysilanes are among the most important reagents in organic chemistry, ranging from being valuable substrates (e.g., C-H arylation, etc.) [6][7][8][9][10] to their most known function as a temporary protective group for hydroxyl moieties (e.g., natural products synthesis, derivatization, etc.). [11][12][13][14] There are several methods of their synthesis, starting with classical condensation between alcohols and halosilanes, [15] and finishing on catalytic coupling reactions with hydro-, [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] vinyl- [33] or allylsilanes, [34,35] and more recently also with silyl formates.…”

Sustainable protocols for direct C–H bond arylation of (hetero)arenes

“…as the oxidant, affording the corresponding mono-arylated products in good yields. 256 Although the present protocol could appear quite convenient from the point of view of Green Chemistry, in our opinion there are actually some drawbacks: first, the need for very large amounts of both catalyst and oxidant, which definitely represent a source of metal contamination of the corresponding coupling products; second, the modest atom economy of the arylsiloxanes, producing significant amounts of siloxane waste that need to be removed by tedious purification procedures.…”

Pivalic Acid‐Assisted Rh(III)‐Catalyzed C−H Functionalization of 2‐Arylpyridine Derivatives Using Arylsilanes

“…Despite the advantageous stability and safe handling, organosilanes have been less explored as the coupling partners in the C−H arylation reaction in comparison with extensively explored organoborons . In 2007, the first example of Pd‐catalyzed C−H bond arylation of acetoanilides by arylsilanes was reported, prompting researchers to explore synthetic utilities of arylsilanes in C−H bond arylation using Ru, Co, Rh, Ir, Ni, Pd, and Au as catalysts. However, N ‐heterocyclic compounds as represented by arylpyridines have rarely been employed as substrates so far (Scheme ) .…”