Photochemistry Enabled C(sp3)–H Borylation of Alkanes and Deboronative Coupling Enabled anti-Markovnikov Hydroalkylation of Unactivated Terminal Olefins

Abstract

Chemists possess long-term interest in organoboron chemistry because boron moieties in organic compounds have the potential to be swapped to almost all functional groups. The first part of this thesis outlines two novel pathways to access organoboronic esters from commercially available aromatic carboxylic acids and alkane derivatives. The essential strategy to achieve both transformations was to harness photo-induced ligand-to-metal charge-transfer (LMCT) process with widely used copper reagents. Second part describes the application of alkyl boronic compounds into a C(sp3)–C(sp3) cross-coupling reaction to build up quaternary carbon centers (QCCs). Furthermore, this protocol could be utilized for an overall hydroalkylation of non-activated alkenes by in situ hydroboration and bimolecular homolytic substitution (SH2), which would provide a unique but efficient approach to QCCs.
Synthesis of aromatic boronic esters from the corresponding carboxylic acids relied on the LMCT of in situ formed carboxylic Cu(II) intermediate to afford aryl pinacol boronic esters with bis(pinacolato)diboron (B2pin2). C(sp3)–H borylation of non-activated alkanes was achieved by the coordinated chlorine radical-enabled hydrogen atom transfer (HAT) process and then borylation with bis(catecholato)diboron (B2cat2). This borylation protocol possesses mild photochemical conditions with satisfied regioselectivity toward terminal C(sp3)–H bond and in the absence of terminal oxidants.
In the second part, a photo-induced radical cross-coupling reaction between primary boronic acids and secondary or tertiary carboxylic redox-active esters was developed. The boronic acid was converted to corresponding boronic catechol ester in situ, which performed as an effective primary radical precursor and coupled with tertiary radical by SH2 strategy. Remarkably, this protocol was further extended to an overall hydroalkylation of non-activated terminal alkenes by a one-pot two-step hydroboration-radical cross-coupling strategy, which represents an unprecedent anti-Markovnikov tertiary and quaternary carbon centers formation from widely existed non-activated terminal olefin groups in diversely functionalized structures.

Date of Award	17 Mar 2026
Original language	English
Awarding Institution	University of Bristol
Supervisor	Varinder K Aggarwal (Supervisor)