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Unformatted text preview: 1 Fijany Layla Fijany Professor Alston Chemistry 12A 28 October 2011 Palladium-Catalyzed Cross Couplings in Organic Chemistry Recently, many new methods of using transitions metals to carry out coupling reactions have been developed. The 2010 Nobel Prize in Chemistry was awarded to three organic chemists (Richard F. Heck, Ei-ichi Negishi, Akira Suzuki) for the development of methods for palladium- catalyzed formation of carbon-carbon bonds via cross-coupling reactions. The formation of new carbon-carbon bonds is of central importance in organic chemistry and a prerequisite for all life on earth. Through the assembly of carbon atoms into chains, complex molecules can be created that are critical for life. The principle of palladium-catalyzed cross couplings is that two molecules are assembled on the metal by the formation of metal-carbon bonds. In this way the carbon atoms bound to palladium are brought very close to one another. In the next step they couple to one another and this leads to the formation of a new carbon-carbon single bond. There are two types of cross- coupling reactions. The two types of reactions are shown in equation 1 and 2. 2 Both reactions are catalyzed by zerovalent palladium and both reactions use an organohalide RX (or analogous compound) as the electrophilic coupling partner. However, the nucleophilic coupling partner differs in the two reactions. In the first type (eq. 1) it is an olefin whereas in the second type (eq. 2) it is an organometallic compound RM. In this way the whereas in the second type (eq....
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This note was uploaded on 02/26/2012 for the course OCHEM 12A taught by Professor Alston during the Fall '11 term at Saddleback.
- Fall '11