Abstract
Abstract A series of chiral ligands were prepared with simple operations from camphorsulfonic acid. They were found to be quite stable to acid and base. These chiral ligands have been employed in the studies of asymmetric reduction of ketones, enantioselective addition of diethylzinc to aldehydes, chiralcyanohydrins and chiral aminonitrile syntheses. In asymmetric reduction of ketones, the chiralsecondary alcohols were produced in 75-94% yield with 19-60% ee by using 3.0 equivalents of chiral ligand 24 and lithiumaluminum hydride. When using 20 mol% of chiral ligand 43 and140 mol% of Ti(OiPr)4 as catalyst to catalyze theenantioselective addition of diethylzinc to aldehydes,the addition products were obtained in 89-99% yield with59-99% ee. For the cyanohydrins synthesis, a mixture of16.5 mol% of chiral ligand 49 and 15 mol% of Ti(OiPr)4 was able to catalyze trimethylsilylcyanide addition to aldehydes in the presence of MS 4A. The chiral cyanohydrins wereobtained in high yield with 88-97% ee. This catalyst was ableto catalyzed aminonitrile formation from aldehydes but without any ee. When (R)-Binol-Et2AlCl (2:1) was used as catalyst and the presence of MS13A, the chiral aminonitrile was synthesizedin high yield with 11% ee.