Iridium-catalyzed C-3 allylation of indoles with allylic alcohols promoted by a bronsted acid

摘要

A highly regioselective method has been developed for the allylation of indoles with an iridium catalyst. This regioselective procedure uses allylic alcohols directly as allylating agents in the presence of a catalytic amount of sulfuric acid. A wide range of indoles reacted smoothly with asymmetrical allylic alcohols to give the corresponding branched products in branched-to-linear ratios of up to 99:1 and yields as high as 92%. A series of inorganic and organic acids were tested in this approach, and it was shown that acids with pK a values in acetonitrile of less than 15 are required in this iridium-catalyzed system.