, as a New Reusable Catalyst for Addition of Trimethylsilyl Cyanide to Carbonyl Compounds

Cyanohydrin trimethylsilyl ethers are versatile intermedi-ates for the synthesis of cyanohydrins, α-hydroxycarboxylic acids, α-hydroxyaldehydes, α,β-unsaturated nitriles and β-aminoalcohols. 1 They are useful for protection of carbonyl groups, 2 and also excellent precursors for ferroelectric liquid crystals 3 and components of commercially important compounds such as the pyrethroid insecticides cypermethrin and fluvalinate. 4 A variety of Lewis acids and Lewis bases have been employed successfully as promoters in cyanosil-ylation of carbonyl compounds. 5 In recent years, several chiral catalysts have been used for asymmetric synthesis of cyanohydrin trimethylsilyl ethers. 6 However, many of these methods suffer from one or more of the following disadvan-tages: long reaction times, vigorous reaction conditions, tedious work up procedures and a need for relatively expensive reagents such as titanium complexes and Schiff bases. These limitations were the motivation for further investigation of a new inexpensive and non-corrosive heterogeneous catalyst for this transformation. Continuing our studies on the application of polyoxo-metalates in organic synthesis, 7 here the use of potassium dodecatungstocobaltate (