Synthesis of a novel chiral Schiff base of (R,R)-11,12-diamino-9,10-dihydro-9,10-ethanonanthracene and its application as ligand in Ti(IV) complex catalyzed asymmetric silylcyanation of aldehydes

A novel chiral salen ligand (R,R)-2 was synthesized through the condensation of (R,R)-11,12-diamino-9,10-dihydro-9,10-ethanoanthracene and 3,5-di-tert-butylsalicylaldehyde. The (salen)Ti(IV) complex formed in situ upon the treatment of ligand 2 and Ti(OPr-i)4 was proved to be an efficient catalyst for the asymmetric trimethylsilylcyanation of aldehydes. The corresponding cyanohydrins were obtained in high yields (75–97%) with moderate to good enantioselectivities (48–76%).