Preliminary Study On Asymmetric Reactions Catalyzed By Chiral Binuclear Metallic Complex

A poly-salen-Ti complex was used as catalyst for the catalytic asymmetric trimethylsilylcyanation of aromatic aldehydes. The adducts of 4-CH3-C6H4CHO and 4-Cl-C6H4CHO were obtained in 82%ee and 93% yield, 82%ee and 98% yield respectively with 1.0mol% catalyst at -40℃. The polymeric catalyst could be recycled for 5 times with the same enantioselectivity.A NOBIN-derived chiral ligand was designed and synthesized. Its zinc complex was applied in asymmetric direct aldol reaction of acetone and p-nitrobenzaldehyde. The product in 32.5%ee and 72% yield was obtained with 20 mol% catalyst at 20℃.Based on the Soai's autocatalytic asymmetric reactions, a reasonable model for autocatalytic asymmetric reaction with dimer of product as catalyst was established. A detailed analysis on chirality amplification by multiplying product was given. The conditions and behavior of chirality amplification in the model reaction was described. Important parameters such as Khomo, Khetero and k for Soai's reactions were obtained by simulation with the reported experimental data.