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Asymmetric Synthesis
 

Asymmetric Synthesis deals with synthesis of chiral molecules, which are non-superimposable on its mirror images. The word chiral comes from the Greek word cheir , which means hand. The chirality can also be referred in wider context. For example, a hand and a foot are chiral and fulfill the same criterion as a chiral molecule. A left hand is a mirror image of the right hand and these cannot be superimposed. Thus, hands are chiral. So, chirality is referred to as handedness. If an organic molecule is chiral, it exists as a mixture of mirror image isomers, which are called Enantiomers. They are given names (R) and (S) based on certain defined rules.

Many drugs and other chemicals come in these two forms, which often behave very differently; one may be active while the other is inactive or even harmful. Thalidomide is a frightening example. It is a chiral molecule, thus every dose of it contained two different forms of the drug. Both are made up of same atoms, but position of the atoms is different (disposition in space). Pregnant women in Europe in the early 1960s took it for the benefit (sedative in this case) of one form but their children suffered from the effects (teratogen in this case) of the other. Since then, the regulatory agency of all the countries framed a law that if a drug molecule is chiral, each enantiomeric form should be synthesized and tested separately before approval is given for its use. In other words, it should be shown that none of the form is harmful. This led to a major emphasis in the development of new methods (enantioselective reactions) for synthesis of one mirror image isomer (enantiomer) in a highly selective manner. In fact, three scientists- Dr. William S. Knowles, Prof. R. Noyori, and Prof. K.B. Sharpless shared the Nobel Prize in the year 2001 for their contribution in this area.

Professor Vinod Singh's research is focused to an area of asymmetric synthesis especially enantioseletive reactions using rationally designed chiral ligands. He has contributed extensively in enantioseletive deprotonation of epoxides and enantioseletive allylic oxidation of olefins. He has also completed total synthesis of several bioactive natural products in chiral form.

More activities about Professor Vinod Singh can be found in
http://home.iitk.ac.in/~vinodks/


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