Deoxygenative Borylation of Secondary and Tertiary Alcohols

Abstract

Two different approaches for the deoxygenative radical borylation of secondary and tertiary alcohols are presented. These transformations either proceed through a metal‐free silyl‐radical‐mediated pathway or utilize visible‐light photoredox catalysis. Readily available xanthates or methyl oxalates are used as radical precursors. The reactions show broad substrate scope and high functional‐group tolerance, and are conducted under mild and practical conditions.

Alternating Radical Stabilities: A Convergent Route to Terminal and Internal Boronates

“…[6,7] We have ourselves produced highly decorated boronates by exploiting the remarkable ability of xanthates to add to av ariety of boronsubstituted alkenes. [6,7] We have ourselves produced highly decorated boronates by exploiting the remarkable ability of xanthates to add to av ariety of boronsubstituted alkenes.…”

Site‐Selective 1,2‐Dicarbofunctionalization of Vinyl Boronates through Dual Catalysis

“…[1] Conventional approaches for their synthesis include transmetalation from well-defined, stoichiometric organometallic reagents and electrophilic boron precursors, [2] hydroboration of unsaturated bonds, [3] and transition-metal-catalyzed borylation reactions of polarized C-(pseudo)halide bonds with bisboron reagents, [4] among others. [5] Recent elegant disclosures have shown the viability of accessing organoboranes via boron-ate complexes, generated from stoichiometric organolithium reagents, with a [1,2]-shift that forges two C À C bonds via one-or two-electron events (Scheme 1, top) [6,7] Despite the advances realized, several challenges remain to be addressed. Among these, a complementary method for triggering a catalytic 1,2-dicarbofunctionalization with simple electrophilic partners that obviates the need for stoichiometric organometallic reagents while enabling rapid, reliable, and modular access to organoboron skeletons would constitute a worthwhile endeavor for chemical invention.…”

Hydride Transfer Enables the Nickel‐Catalyzed ipso‐Borylation and Silylation of Aldehydes

“…Regarding these drawbacks, researchers are focused on designing viable substrates which can be converted into boronate esters. [5][6][7][8][9] Recently, innovative strategies using carboxylic acid derivatives have been developed and the transition-metal-catalyzed decarbonylative borylation of carboxylic acid derivatives has been accomplished. [10] However, additional steps such as esterification, thioesterification and amidation are required for their synthesis from carboxylic acids.…”

“…[a] [a] Reaction conditions: 1 (0.2 mmol), 2 (0.24 mmol), [Ni(cod) 2 ] (0.01 mmol), P(Oct) 3 (0.02 mmol), 3 c (0.3 mmol), toluene (1 mL), 160 8C, 36 h, yield after isolation. key hydrogen-transfer process to form acylnickel(II) alkoxide D. The resulting complex D undergoes a transmetallation step with bis(pinacolato)diboron (2) or dimethyl(phenyl) (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)silane (5), in the latter case, the step being facilitated by the KF. The subsequent CO extrusion releases intermediate F. Finally, reductive elimination leads to the borylated or silylated products while regenerating the active Ni 0 species coordinating to ketone 3 which then initiates a next catalytic cycle.…”