Electrooxidative Activation of B-B Bond in B2 cat2 : Access to gem-Diborylalkanes via Paired Electrolysis.

This report describes the unprecedented electrooxidation of a solvent (e.g., DMF)-ligated B2 cat2 complex, whereby a solvent-stabilized boryl radical is formed via quasi-homolytic cleavage of the B-B bond in a DMF-ligated B2 cat2 radical cation. Cyclic voltammetry and density functional theory provide evidence to support this novel B-B bond activation strategy. Furthermore, a strategy for the electrochemical gem-diborylation of gem-bromides via paired electrolysis is developed for the first time, affording a range of versatile gem-diborylalkanes, which are widely used in synthetic society. Notably, this reaction approach is scalable, transition-metal-free, and requires no external activator.

Electrochemical Borylation of Alkyl Halides: Fast, Scalable Access to Alkyl Boronic Esters.

Herein, a fast, scalable, and transition-metal-free borylation of alkyl halides (X = I, Br, Cl) enabled by electroreduction is reported. This process provides an efficient and practical access to primary, secondary, and tertiary boronic esters at a high current. More than 70 examples, including the late-stage borylation of natural products and drug derivatives, are furnished at room temperature, thereby demonstrating the broad utility and functional-group tolerance of this protocol. Mechanistic studies disclosed that B2cat2 serves as both a reagent and a cathodic mediator, enabling electroreduction of difficult-to-reduce alkyl bromides or chlorides at a low potential.

Electrochemical Oxidation Enables Regioselective and Scalable α-C(sp3)-H Acyloxylation of Sulfides.

A highly selective, environmentally friendly, and scalable electrochemical protocol for the construction of α-acyloxy sulfides, through the synergistic effect of self-assembly-induced C(sp3)-H/O-H cross-coupling, is reported. It features exceptionally broad substrate scope, high regioselectivity, gram-scale synthesis, construction of complex molecules, and applicability to a variety of nucleophiles. Moreover, the soft X-ray absorption technique and a series of control experiments have been utilized to demonstrate the pivotal role of the self-assembly of the substrates, which indeed is responsible for the excellent compatibility and precise control of high regioselectivity in our electrochemical protocol.

Exogenous-oxidant-free electrochemical oxidative C-H phosphonylation with hydrogen evolution.

We herein report a versatile and environmentally friendly electrochemical oxidative C-H phosphonylation protocol. This protocol features a broad substrate scope; not only C(sp2)-H phosphonylation, but also C(sp3)-H phosphonylation is tolerated well under exogenous-oxidant-free and metal catalyst-free electrochemical oxidation conditions.