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Iridium-Catalyzed Hydrocarboxylation of 1,1-Dimethylallene:  Byproduct-Free Reverse Prenylation of Carboxylic Acids

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journal contribution
posted on 07.02.2008, 00:00 by In Su Kim, Michael J. Krische
Exposure of carboxylic acids 1a12a to commercially available 1,1-dimethylallene in the presence of substoichiometric quantities of an iridium catalyst prepared in situ from [Ir(cod)Cl]2 and BIPHEP provides the corresponding 1,1-dimethylallyl (reverse prenyl) esters 1b12b in 74−92% isolated yield. This protocol represents the first branch-regioselective allene hydrocarboxylation. Stoichiometric byproducts are not generated in this process and protecting groups are not required for alcohols, phenols, and indolic amines.