2 rhodium-catalysed cyclopropanation. We found that these hetero [3.1.1]propellanes are stable towards isolation and storage, but amenable to a range of radical ring-opening reactions, leading to bridgehead-disubstituted hetero-bicyclo [3.1.1]heptanes that cannot be accessed using alternative methods. Given the importance of heterocyclic scaffolds in pharmaceutical design, and the evergrowing popularity of rigid small ring building blocks, we expect these unprecedented heteropropellanes will be of exceptional utility in drug discovery programmes.