ORGN 11 |
| Palladium-catalyzed multicomponent coupling reactions serve as powerful tools for the construction of complex organic molecules. For this reason, studies aimed at incorporation of novel organopalladium intermediates into multicomponent coupling schemes have the potential to uncover valuable new synthetic protocols. Bis-pi-allylpalladium complexes remained notably underutilized as intermediates in organic synthesis. We envisioned that allylpalladium(II) dimer catalysts featuring a “nontransferable” auxiliary allyl ligand could react with allenes and organometallic reagents (boronic acids) to assemble in situ an unsymmetrical bis-pi-allylpalladium complex capable of a regioselective transfer of the “preassembled” allyl fragment to organic electrophiles (aldehydes and imines). In this presentation, development of this methodology, and its application to regio- and diastereocontrolled synthesis of substituted branched homoallylic alcohols and unnatural amino acids, as well as alpha, beta-unsaturated-delta-lactones, will be described. Progress in elaboration of the products into medicinally relevant heterocycles, including bioactive lignans and neuroexitatory amino acids will also be presented. |
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Allenes in Synthesis
8:00 AM-12:00 PM, Sunday, 26 March 2006 Georgia World Congress Center -- C303/304/305, Oral
Division of Organic Chemistry |