ORGN 31 |
| Phosphinooxazolines, first employed by Williams, Pfaltz, and Helmchen, serve as versatile ligands for a variety of asymmetric catalytic reactions. The hydroxy group in hydroxy-containing phosphinooxazolines such as 1 can take part in hydrogen bonding to low valent metal ions, thereby affecting the conformation and, as a result, the stereochemistry of catalytic reactions. The hydroxy group is also capable of coordinating to high valent metal ions via the oxygen atom, resulting in more rigid complexes. This leads for example to enhanced enantioselectivity in Rh- and Ir-catalyzed hydrosilylations of prochiral ketones. The influence of these secondary interaction on the conformation and dynamics of metal complexes and on the selectivity in catalytic reactions will be discussed.
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Metal-Mediated Reactions and Syntheses
8:00 AM-12:00 PM, Sunday, August 19, 2007 BCEC -- 254 A/B, Oral
Division of Organic Chemistry |
