Copper(II) and Bismuth(III) Hydroxide Catalyzed Addition Reactions of Hydrazonoester with Allenylboronate in Aqueous Media

Metal-hydroxide-catalyzed addition reactions of hydrazonoester with allenylboronate in aqueous media are described. The propargyl adduct was obtained selectively by using copper(II) hydroxide, whereas the allenyl adduct was produced preferentially using bismuth(III) hydroxide in water-DMF (1:3). The reactions proceeded smoothly in pure water without the use of any organic solvents by addition of a small amount (1.7 mol%) of sucrose.