ORGN 8 |
| Our interest in the application of nitrenium ions intermediates to organic synthesis has recently led to the discovery of a novel and highly versatile method for the preparation of 5, 6, 7 and 8-membered hydroxy lactams, such as 5. Treatment of ω-unsaturated O-alkyl hydroxamates 1 with phenyliodine(III) bis(trifluoroacetate) (PIFA) mediates an intramolecular oxamidation process to form trifluoroacetate esters 4, which can be hydrolyzed in-situ to provide the corresponding alcohols 5 in excellent overall yield. In light of our on-going investigations, we believe that this transformation proceeds through the intermediacy of an acyl nitrenium ion 2 that undergoes concerted alkene cycloaddition to generate 3. Regioselective ring opening of this bicyclic aziridinium ion would then generate the observed products. Evidence to support the proposed mechanism and our application of this reaction to the total synthesis of alkaloid natural products, including the nicotinic agonist epiquinamide, will be presented.
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ACS Award for Creative Research and Applications of Iodine Chemistry
8:10 AM-12:00 PM, Sunday, 13 March 2005 Convention Center -- Ballroom 20 C-D, Oral
Division of Organic Chemistry |
