Sc(OTf)(3), an efficient catalyst for addition of allyltrimethylsilane to aldehydes; Chemoselective addition to aldehydes in presence of ketones and in situ acylation (3 component coupling)

Scandium triflate (2-10 mol%) has been found to be a highly efficient catal yst for the addition of allyltrimethylsilane to both activated aromatic and aliphatic aldehydes. However, deactivated (electron rich) aromatic aldehyd es gave double allylated products instead. Using a stoichiometric amount of Ac2O in the allylation reaction led directly to homoallylic acetates [in s itu acylation catalysed by Sc(OTf)(3)] and for the first time gave high yie lds of adducts with moderately electron rich aromatic aldehydes.