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| Vladimir Prelog was born in Sarajevo (Bosnia-Herzegovina), which then belonged to the Austrian-Hungarian Monarchy and later, in 1918, became part of Yugoslavia. At the beginning of the first World War, in 1915, he moved to Zagreb, the capital of Croatia, where he attended the gymnasium. The period 1924 to 1929 was spent studying Chemistry at the Czech Institute of Technology in Prague, Czechoslovakia. The supervisor of his thesis was Professor Emil Votocek, one of the prominent founders of chemical research in Czechoslovakia. His mentor, however, was Rudolf Lukes, then lecturer and later successor of Votocek to the chair of organic chemistry. He received early training at the University of Zagreb, then the Ph.D. at the Institute of Technology in Prague (1929). After a time on the faculty at Zagreb he moved to the Swiss Federal Institute of Technology (ETH) in Zurich, where he, as director of the organic laboratory, followed in a long line of Nobelists (Willstätter, Staudinger, Kuhn and Ruzicka). Prelog was a superb teacher and lecturer, and was the recipient of many honors, among them the 1967 Davy Medal of the Royal Society and the 1969 Roger Adams Award of the ACS, in a long career. Prelog is probably best known to organic chemistry students for his work on the nomenclature of stereoisomers, the CIP or Cahn-Ingold-Prelog sequence rules for the unambiguous assignment of absolute configuration at a stereogenic center. But in his research, Prelog had a long-standing experimental interest in stereochemistry as well. He worked on the Cinchona alkaloids, especially quinine and compounds related to its quinuclidine moiety. His synthesis of the diamond-like hydrocarbon adamantane brought him international recognition. He elucidated the structures of antibiotics such as nonactin and rifamycins. Perhaps most important was his synthesis of medium sized rings with 8-12 members, studies of their conformations and trans-annular interactions, and of the limits to Bredt's Rule (a double bond at a bridgehead position is possible if the ring is large enough). Prelog received the 1975 Nobel Prize in Chemistry (shared with J. W. Cornforth). for his application of X-ray analysis techniques to the determination of the structures of many types of complex organic molecules, such as antibiotics, and for formulating systematic rules that relate molecular structure to the properties of chemical compounds. | ||
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| Cahn- Ingold- Prelog Sequence Rules | ||
| The letters used to assign absolute
stereochemistry based on the 'Cahn, Ingold, Prelog' 'Sequence Rules'.
After assigning priorities to the substitutuents around an asymmetric
centre the molecule is viewed such that the bond from the asymmetric
centre to the substituent of lowest priority (4) is going away from the
viewer, or into the page.
If the remaining three groups from highest to lowest priority (1-2-3) appear clockwise then the asymmetric centre is designated as R. If the remaining three groups from highest to lowest priority (1-2-3) appear anticlockwise then the asymmetric centre is designated as S. R - rectus - right -
clockwise
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R*/S*(see also Erythro- and Threo-) |
