Metal‐Free Electrochemical Hydroboration of Olefins

Abstract

Herein, we reported the electrochemical hydroboration of olefins to access the organoboron derivatives in a one-pot reaction under air and at room temperature. This reaction manifold was applied to a broad range of alkenes with 40-90% yields and good functional group tolerance without using a metal catalyst or an additional hydride source. Mechanistic studies suggested that this anodic oxidation conducted in an undivided cell allowing the production of a boron radical species, which initiates the hydroboration of olefins event by a radical addition process.

Electrochemical Annulation of ortho‐Alkynylbiphenyls to Fused Sulfenyl Phenanthrenes and Spiro Cyclohexenone Indenes

“…By precisely changing the applied electrode potential, it would become possible to promote electro‐organic transformations, generally at room temperature, compared to traditional techniques, which usually progress in the presence of strong oxidizing/reducing reagents and elevated temperatures. This electrochemical approach might be useful in terms of simple implementation, precision control, and good substrates’ compatibility [9–13] . As a result, electro‐organic synthesis holds more significant economic and good functional group tolerance [14,15] …”

“…This electrochemical approach might be useful in terms of simple implementa-tion, precision control, and good substrates' compatibility. [9][10][11][12][13] As a result, electro-organic synthesis holds more significant economic and good functional group tolerance. [14,15] Phenanthrenes are an important class of aromatic compounds due to their numerous biological properties, including their ability to fight against cancer, HIV, and bacteria; also, it was abundantly prevalent in many natural products and physiologically active compounds.…”

Radical hydroboration for the synthesis of organoboron compounds

“…Similarly, the Yang and Xia group also disclosed the radical hydroboration of activated alkenes using modified reaction conditions (Scheme 21). 54 In their reaction, iron was used as the anode and aluminium as the cathode, with potassium tert -butoxide as the base, and tetrabutylammonium bromide as the electrolyte in the DMA solvent. Mechanistic studies provided evidence to suggest the oxidation of the B 2 pin 2 −O t -Bu ate complex, which released Bpin radicals for addition to alkene.…”

“…Remarkably, the reaction of unactivated alkenes gave the Markovnikov product instead, which was postulated to react through different mechanistic pathways. 54,55…”