Whittaker AM, Lalic G * University of Washington, Seattle, USA
Monophasic Catalytic System for the Selective Semireduction of Alkynes.
Org. Lett. 2013;
15: 1112-1115
Key words
copper - polymethylhydrosiloxane - alkynes
Significance
A novel copper-catalyzed semireduction of alkynes to alkenes has been disclosed. 0.5 to 2 mol% of a copper catalyst in combination with polymethylhydrosiloxane and isobutyl alcohol efficiently reduced terminal and internal alkynes, even in the presence of nitro and iodo groups.
Comment
The authors propose the following mechanism: the silane transfers its hydride to the copper catalyst and a subsequent hydrocupration of the alkyne takes place. Protonation of this alkenyl-copper intermediate by the alcohol forms a copper alkoxide and the desired product.
