Recent Progress in Coupling Reactions Involving the Novel Substrate of Bicyclo[1.1.0]butane (BCB).

Bicyclo[1.1.0]butanes (BCBs) possess high ring strain and unique structural rigidity, making them versatile building blocks for constructing three-dimensional (3D) molecular frameworks. This review primarily focuses on the latest research advances in BCB since 2019, including cyclobutylation reaction, cyclization reaction, ring-opening reaction, and direct cross-coupling reaction. Mechanistic analysis centers on activation modes such as single-electron transfer, hydrogen atom transfer, and force-promoted cleavage, alongside selectivity control mechanisms including ligand-directed regional selectivity, chiral catalysis-mediated enantioselectivity, and minimization of dipole repulsion. Multiple systems have achieved highly efficient BCB functionalization and broad substrate compatibility.