Borylcyclopropanes: Synthetic Strategies and Applications

Abstract

ABSTRACT The carbon–boron bond is among the most versatile functional groups in organic synthesis, and its installation within the strained cyclopropane framework generates borylcyclopropanes with a rich reactivity profile. The presence of a boron moiety on the cyclopropane ring unlocks a broad spectrum of transformations inaccessible to unfunctionalized cyclopropanes, including Suzuki–Miyaura cross‐coupling, oxidation, amination, Matteson homologation, and stereospecific ring‐opening via 1,2‐metalate rearrangement to enantioenriched acyclic organoboron arrays. Meanwhile, the distinctive reactivity of boron‐stabilized intermediates such as α‐boryl radicals, α‐boryl carbanions, and α‐boryl cations enables cyclopropanation strategies with no classical counterpart. This review provides an exhaustive survey of borylcyclopropane chemistry, organized by mechanistic class: metal–carbene cyclopropanations under palladium, copper, rhodium, and enzyme catalysis; non‐diazo carbene and carbenoid approaches; transition‐metal‐catalyzed and metal‐free intramolecular nucleophilic cyclizations; photocatalytic radical pathways; iridium‐ and palladium‐catalyzed C─H borylation; hydroboration of cyclopropenes and alkylidenecyclopropanes; and miscellaneous strategies including bicyclo[1.1.0]butane (BCB) ring‐opening and 1,2‐metalate rearrangements. Applications in medicinal chemistry, natural product synthesis, and the preparation of stereodefined acyclic building blocks are also discussed.