Several chemical molecules can co-exist in nature along with their mirror counterparts. Two compounds, akin to hands, can be composed of same atoms to be structurally similar but with opposite orientations. This phenomenon termed as chirality can impart entirely different chemical properties to mirror counterparts. A classic example of chirality is thalidomide, which was originally commercially available as a mixture of enantiomers. While one is a harmless sedative, the other highly toxic to fetuses leading to disturbing congenital abnormalities.
Hence, it has become imperative to create compounds with high optical purity to be a measure of chiral purity. This is indicative of greater amount of enantiomer in one over the other. However, due to small structural differences and identical stability between enantiomers, creating one over the other is challenging.
Researchers Devise New Desymmetrization Strategy to create Enantiomers
Desymmetrization of a non-chiral compound similar in characteristic to the target molecule is one way of synthesizing enantiomers. The process involves modifying a molecule so as to lose the symmetry characteristics that prevented it from being chiral.
At Jérôme Waser’s Catalysis and Organic Synthesis Laboratory, researchers have devised a new desymmetrization plan to access chiral building blocks that contain urea sub-structures. Biomolecules such as biotin or bioactive natural products contain urea derivatives such as anticancer agelastatin. The research led to two crucial innovations; first, design of a non-chiral cyclopropane precursor. The new molecule provides enhanced reactivity and is best-suited for reactions under mild conditions.
The second innovation involved engineering a new copper catalyst that can combine to form an enantiomer of high selectivity of the desired product.