Cu-Catalyzed Carbometallation of Propargylic Alcohols by Grignard Reagents

Significance

Herein, an optimized protocol for the highly regioselective carbometallation of terminal secondary propargylic alcohols by alkylmagnesium bromides is described. The reaction is catalyzed by copper salts and is completely anti-stereoselective. The conservation of the chiral information is observed, if an enantiopure substrate is used. The resulting vinylmagnesium species can be used further in Kumada coupling reaction or trapped by iodine to form (Z)-alkenyl iodides. For the latter, some further synthetic transformations are desribed.