Ruthenium-catalyzed enantioselective propargylation of indoles with propargylic alcohols affords the corresponding beta-propargylated indoles in good yields with a high enantioselectivity (up to 95% ee). A remarkable effect of the nature of the N-substituent of indoles is observed for the enantioselectivity of the propargylated indoles. The preparative method described in this paper may provide a novel protocol for asymmetric Friedel-Crafts alkylation of indoles using propargylic alcohols as a new type of electrophiles.
Ruthenium-Catalyzed Enantioselective Propargylation of Indoles with Propargylic Alcohols
Ruthenium-catalyzed enantioselective propargylation of l-(triisopropylsilyl)-1H-indoles with propargylicalcohols gives the corresponding β-propargylated indoles in good yields with high enantioselectivity. Reactions with l-(l-naphthyl)prop-2-yn-l-ol achieve the highest enantioselectivity (up to 95% ee).