Regio- and enantiospecific rhodium-catalyzed allylic etherification reactions using copper(I) alkoxides: influence of the copper halide salt on selectivity.

The transition metal-catalyzed allylic etherification represents a fundamentally important cross-coupling reaction for the construction of allylic ethers. We have developed a new regio- and enantiospecific rhodium-catalyzed allylic etherification of acyclic unsymmetrical allylic alcohol derivatives using copper(I) alkoxides derived from primary, secondary and tertiary alcohols. This study demonstrates that the choice of copper(I) halide salt is crucial for obtaining excellent regio- and enantiospecificity, providing another example of the effect of halide ions in asymmetric transition metal-catalyzed reactions. Finally, the ability to alter the reactivity of the alkali metal alkoxides in this manner may provide a useful method for related metal-catalyzed cross-coupling reactions involving heteroatoms.