Platinum-catalyzed multi-step reaction of propargyl alcohols with N-heteroaromatics.

N-Methyl indole reacts with but-2-yn-1-ol in the presence of PtCl(2) in MeOH giving indole derivatives having a substituted 3-oxobutyl group at the 3-position in good yield. Under the reaction conditions, various substituted indoles and substituted propargyl alcohols are successfully involved in the reaction giving the corresponding addition products in good to moderate yields. The catalytic reaction can be further extended to N-phenyl pyrrole. In the present multi-step reaction, PtCl(2) likely plays dual roles: as the catalyst for the rearrangement of propargyl alcohols to the corresponding alkenyl ketones and as the catalyst for the addition of indoles to the alkenyl ketones. Experimental evidence is provided to support the proposed mechanism.