Ruthenium-catalyzed enantioselective [3+3] cycloaddition of propargylic alcohols with 2-naphthols affords the corresponding cycloaddition products in moderate to good yields with a high enantioselectivity (up to 99% ee). This cycloaddition proceeds via stepwise reactions of propargylation and intramolecular cyclization, where ruthenium-allenylidene and -vinylidene complexes work as reactive intermediates, respectively.
Ruthenium-Catalyzed Asymmetric Propargylic Substitution Reactions of Propargylic Alcohols with Acetone
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.