Application of polysalen-ti(IV) complex for asymmetric cyanosilylation of benzaldehyde and its derivatives

As a versatile intermediate, chiral alpha-cyanohydrins can be synthesized by asymmetric trimethylsilylcyanation of aldehydes. Schiff base-Ti complexes have been proven to be excellent catalysts for this reaction. Polysalen-Ti (IV) complex was successfully used in asymmetric trimethylsilylcyanation of benzaldehyde and its substitutes. The adducts of trimethylsilylcyanation of 4-CH3-C6H4CHO and 4-Cl-C6H4CHO were obtained with ee = 82 %, yield = 93 %, and ee = 82 %, yield = 98 %, respectively, at -40 degreesC. The catalyst could be recycled for 5 times while maitaining its activity and enantioselectivity at 20 degreesC.