Iridium-catalyzed hydrocarboxylation of 1,1-dimethylallene: byproduct-free reverse prenylation of carboxylic acids.
Exposure of carboxylic acids 1a-12a 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 1b-12b 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.
Kim
In Su
IS
University of Texas at Austin, Department of Chemistry and Biochemistry, Austin, Texas 78712, USA.
Krische
Michael J
MJ
D000466:Alkadienes / Q000737:chemistry; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D004952:Esters; D007495:Iridium / Q000737:chemistry*; D015394:Molecular Structure; D054876:Prenylation; D013237:Stereoisomerism
D000466:Alkadienes; D002264:Carboxylic Acids; D004952:Esters; D007495:Iridium; C025947:propadiene