A solution to the anti-Bredt olefin synthesis problem

The π-bonds in unsaturated organic molecules are typically associated with having well-defined geometries that are conserved across diverse structural contexts. Nonetheless, these geometries can be distorted, leading to heightened reactivity of the π-bond. Although π-bond–containing compounds with bent geometries are well utilized in synthetic chemistry, the corresponding leveraging of π-bond–containing compounds that display twisting or pyramidalization remains underdeveloped. We report a study of perhaps the most notorious class of geometrically distorted molecules that contain π-bonds: anti-Bredt olefins (ABOs). ABOs have been known since 1924, and conventional wisdom maintains that ABOs are difficult or impossible to access. We provide a solution to this long-standing problem. Our study also highlights the strategic manipulation of compounds that display considerable distortion arising from the presence of geometrically constrained π-bonds.