ORGN 128 |
| The palladium(II)-BINAP catalyzed enantioselective carbonyl-ene reactions between six arylglyoxals and four alkenes were investigated demonstrating good to excellent enantioselectivities. The six arylglyoxals include phenylglyoxal, 4-methylphenylglyoxal, 4-chlorophenylglyoxal, 4-bromophenylglyoxal, 2,4,6-trimethylphenylglyoxal and 2-naphthylglyoxal; The four alkenes include methylenecyclohexane, 2,3-dimethyl-1-butene, 2,4,4-trimethyl-1-pentene and a-methylstyrene. In comparison with arylglyoxals, alkenes have greater influence on the enantioselectivity. Among the six arylglyoxals, 2,4,6-trimethylphenylglyoxal demonstrates the highest average ee value(88.1%), while the 2-naphthylglyoxal demonstrates the lowest average ee value(81.9%). The average ee values of phenylglyoxal and 4-methylphenylglyoxal are good and comparable(87.0% and 86.7%, respectively). 4-chlorophenylglyoxal and 4-bromophenylglyoxal result in slightly decreased average ee values (82.0% and 83.7%, respectively). Among the four alkenes, 2,3-dimethyl-1-butene demonstrates excellent average ee value high up to 91.7% which is the highest average ee values among the four alkenes. While alpha-methylstyrene demonstrates the lowest average ee value(77.9%). 2,4,4-trimethyl-1-pentene and methylenecyclohexane demonstrate good and comparable average ee values(85.5% and 84.5%, respectively). |
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Asymmetric Reactions and Syntheses, Metal-Mediated Reactions, Combinatorial, Parallel, and Solid-Phase Chemistry
8:00 PM-10:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster
Division of Organic Chemistry |