Recent advances in the synthesis of bicyclo[4.1.1]octanes.

The exploration of bicyclo[n.1.1]alkanes, known for their intricate chemical diversity and potential as benzene bioisosteres, has garnered significant attention over the past two decades. In particular, the past year has seen the emergence of bicyclo[4.1.1]octanes and their structural analogues as promising bioisosteres for meta-substituted arenes and cis-1,3-disubstituted cyclohexanes. To meet the growing demand for bicyclo[4.1.1]octanes, chemists have recently developed innovative (4 + 3) cycloaddition strategies, leveraging bicyclobutanes (BCBs) and 1,4-dipoles for their synthesis. This review provides a comprehensive evaluation of recent advancements in the synthesis and functionalization of these compounds, emphasizing their scope and underlying mechanisms. Additionally, we highlight the challenges and future prospects of identifying novel reaction pathways to access new functionalized bicyclo[4.1.1]octanes.