Highly efficient double-activation catalysts for the synthesis of ketone cyanohydrins

Tertiary cyanohydrin trimethylsilyl ethers were synthesized in excellent chemical yields by using salen-Al complex (0.25 mol%) and N-oxide (0.5 mol%) without solvent at ambient temperature. The relationship between the ligand structure and catalyst efficiency is discussed. Preliminary mechanistic studies were carried out, and transition states were proposed accounting for the action of the double-activation catalysts