A group of researchers from the University of California at Los Angeles has achieved a groundbreaking scientific feat by overturning a rule that has been considered irrefutable in organic chemistry for nearly a hundred years. The scientists successfully synthesized a molecular structure that contradicts the postulate proposed by German chemist Julius Bredt in 1924 (source).
The foundation of organic chemistry lies in carbon, an element with the unique ability to form connections with nearly all other elements on the periodic table. This characteristic has been crucial for the emergence and evolution of life on Earth. Despite carbon’s versatility, there are still boundaries to its capabilities that current scientific research continues to expand.
According to Bredt’s rule, stable double covalent bonds cannot form near V-shaped bridge structures in bicyclic molecules. For over ninety years, very few experiments have challenged the validity of this statement.
Professor Nil Garg, the leader of the study, and his team developed a new approach to tackle this long-standing problem. They initially conducted a theoretical analysis of various types of bicyclic rings with an anti-Bredt connection, following the methodology of renowned chemist Shu Kobayashi.
During the experiments, the researchers used a comprehensive method involving Silil (Pseudo) halide precursors combined with fluoride-containing compounds. The introduction of specific stabilizing components not only allowed for the synthesis but also the detection of olefins – organic compounds with double carbon-carbon bonds. This double bond, situated in a specific location within the bicyclic molecule, was previously deemed “impossible” according to Bredt’s rule.
The specific bicyclic molecule synthesized by the team is Norbornene, taking on an eight-like shape with a central carbon atom resulting in a bridgehead peak, altering the spatial configuration of the structure.
Nil Garg points out a paradox where many chemists have overlooked anti-Bredt olefins in their research. He believes that such limitations should be viewed as guidelines rather than unchanging laws, providing a broader scope for scientific exploration.
The achievement by the California chemists paves the way for the development of novel drugs based on three-dimensional structures. These synthesized structures could serve as a foundation for the next generation of pharmaceuticals and encourage a reevaluation of other established principles