Ring-Strain-Promoted Transformations of Bicyclo/Azabicyclo[1.1.0]butane-Derived Boronic Esters

Bicyclo[1.1.0]butane-andazabicyclo[1.1.0]butane-derivedboronic esters (BCB-Bpins) combine high ring strain with the versatile reactivity of organoboron groups, and their transformations are typically driven by strain release.This review summarizes recent advances in BCB-Bpin chemistry through three main pathways: ionic pathways, such as nucleophilic 1,2-shift in boronate complexes; radical approaches, including strain-release-driven additions to BCB-Bpins; and transitionmetal-catalyzed stereoselective functionalizations, especially Pd-and Ir-catalyzed stereoselective and asymmetric difunctionalizations. Representative studies, mechanistic features, selectivity control, current challenges, and future opportunities are also discussed.