Borylation of Unactivated C(sp³)–H Bonds with Bromide as a Traceless Directing Group

Abstract

A palladium-catalyzed alkyl C−H borylation with bromide as a traceless directing group is described, providing a convenient approach to access alkyl boronates bearing a β-allcarbon quaternary stereocenter. The protocol features a broad substrate scope, excellent site selectivity, and good functional group tolerance.

Remote C(sp3)–H activation: palladium-catalyzed intermolecular arylation and alkynylation with organolithiums and terminal alkynes

“…On the basis of both our aforementioned results and previous studies reported in the literature, [2][3][4][5][6][7][8][9][10][11] we proposed a mechanism for the palladium-catalyzed C(sp 3 )-H activation coupling reaction proceeding by a 1,4-Pd shift (Scheme 6). Initially, the Pd (0) catalyst coordinates to substrate 1a providing intermediate A, which undergoes oxidative addition to generate Pd(II) intermediate B.…”

“…In the past two decades, palladium-catalyzed activation of remote C(sp 3 )-H has emerged as a powerful method for the construction of a variety of C-C bonds, 1 most of which rely on the deployment of the 1,4-palladium shift strategy. 2,[5][6][7][8][9][10][11] As can be seen in Scheme 1, the in situ-generated diorganopalladacycle A via oxidative addition of Pd(0) to a C(sp 2 )-X bond and further cleavage of the proximate intramolecular C(sp 3 )-H bond leads to potential transformations. Alternatively, the ring-opening of palladacycle A through protonation or oxidative addition/reductive elimination provides an σ-alkylpalladium complex B, hence resulting in an overall 1,4-palladium shift as initially observed by Dyker.…”

“…6 b Soon after, Lin and co-workers reported a palladium-catalyzed alkyl C–H borylation with aryl bromides, furnishing alkyl boronates. 7 It must also be pointed out that Luan, 8 Zhang, 9 Martin 10 and Yang 11 have all contributed significantly to the palladium-catalyzed activation of inert C(sp 3 )–H bonds.…”

Highly Stereoselective Synthesis of 2,2‐Disubstituted Vinylphosphonates via Aryl to Vinyl 1,4‐Palladium Migration

“…Scheme 2 Gram-scale preparation Based on the above experimental results and previous reports, [13][14]17] a tentative catalytic cycle is proposed as shown in Scheme 3. The initial oxidative addition of aryl bromide 1a to palladium(0) generates the intermediate A.…”

Photoinduced metal-free borylation of aryl halides catalysed by an in situ formed donor–acceptor complex

“…Visible light catalysis 5 has become a well-accepted and powerful method for the direct borylation of drug like molecules. Seminal studies by Larionov, 6 Aggarwal, 7 Wu, 8 Schelter 9 and others 10 have established the viability and synthetic utility of this approach, circumventing the need for well recognized photocatalysts and metal additives. Studer 11 developed radical borylation of aryl iodides with bis(catecholato)diboron (B 2 cat 2 ) as the boron source under mild conditions.…”