ORGN 528 |
| Recent reports have highlighted the efficiency of simple Brfnsted acids in catalyzing difficult organic reactions. These new catalytic pathways have been shown to expand the substrate scope of many reactions. Triflic acid is one such catalyst. Recently, it has been shown to efficiently catalyze the addition of deactivated allylboronates to aldehydes in a tandem allylation/lactonization process. The stereoselectivity of the reactions between isomeric allylboronates 1 or 2 and various aldehydes to form lactones 3 has been studied. With 1, the cis isomer of products 3 should be favoured. However, in some cases, the trans isomer is isolated as the major product. Intriguingly, the reaction of 2 under identical conditions also leads to the trans isomer. Mechanistic work using isotope labelling was done to determine the origin of the stereoselectivity. Furthermore, preliminary studies have been initiated to expand this methodology with various internal nucleophiles to form heterocycles in a stereoselective manner.
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New Reactions and Methodology, Heterocycles and Aromatics, Bioorganic Chemistry
8:00 PM-10:00 PM, Tuesday, 12 September 2006 Moscone Center -- Hall D, Poster
Division of Organic Chemistry |
