Indium(III) bromide catalyzed rapid propargylation of heteroaromatic systems by α-aryl-substituted propargyl alcohols

A variety of heteroaromatic compounds such as indole, carbazole, pyrrole, and furan underwent smooth coupling with propargylic alcohols in the presence of 10 mol% of indium(III) bromide under mild conditions to furnish exclusively propargylated heterocycles in excellent yields and high regioselectivity. The use of indium(III) bromide makes this procedure simple, convenient, and practical. The hydroxy groups of the propargylic alcohols were simply replaced by the nucleophiles in an S(N)2' manner.