Chemoselective aldol reaction of silyl enolates catalyzed by MgI(2) etherate.
Mukaiyama-type aldol coupling of typical silyl enolates 2-4 with aryl or vinyl aldehydes and acetals was realized in the presence of 1-5 mol % of MgI(2) etherate (1) in a mild, efficient, and highly chemoselective manner. Iodide counterion, weakly coordinating peripheral ethereal ligands (Et(2)O) of Mg(II), and a noncoordinating reaction media (i.e. CH(2)Cl(2)) are among the critical factors for the unique reactivity of this catalytic system. [reaction: see text]