UCLA Chemists Have Created “Impossible” 3D Bonds That Shouldn’t Exist
Summary
UCLA chemists challenge long-standing principles of organic chemistry, demonstrating that breaking traditional rules can lead to the creation of new molecules. This groundbreaking research opens exciting possibilities for future chemical innovations and molecular design.
Key Insights
What are these 'impossible' 3D bonds, and why were they thought impossible?
The 'impossible' 3D bonds refer to highly strained double bonds in cage-shaped molecules like cubene and quadricyclene, which defy traditional expectations of flat alkene geometry due to their rigid 3D structures. These were considered impossible because their bridgehead positions violate Bredt's rule, a 100-year-old principle stating that double bonds cannot stably exist at ring junctions in bridged bicyclic systems, as the bonds would be too twisted and unstable.
How did the UCLA chemists create and use these unstable molecules?
The researchers synthesized stable precursors with silyl groups and leaving groups, then treated them with fluoride salts to generate the short-lived cubene and quadricyclene molecules in situ. These highly reactive, hyperpyramidalized intermediates were immediately trapped by adding other reactants, forming stable, complex 3D products useful for applications like drug development.