Borylation of phenols using sulfuryl fluoride activation

Abstract

Boronic esters find increasing applications as key starting materials and central intermediates in organic synthesis. Their synthesis from highly abundant and renewable feedstocks continues to be interesting. Here, we report an efficient and one-pot method for the synthesis of aryl/heteroaryl boronic esters from phenols. In this approach, phenols are first activated by sulfuryl fluoride to form aryl fluorosulfonates, followed by a palladium-catalyzed deoxygenative borylation reaction with bis(pinacolato)diboron to provide a series of boronic esters. This methodology exhibits excellent functional group tolerance and is applicable for the synthesis of natural products and current drug molecules. In addition, this protocol is also amenable for the borylation of biomass derived phenols, including naturally occurring and bioactive compounds. Notably, a novel boronate-based NIR fluorescent probe HTCPB was synthesized using this procedure and successfully employed in fluorescence bioimaging of H₂O₂ in mouse mammary cancer cells.