Asymmetric Reaction Catalysed By Bifunctional Salen Compounds And Chiral Diamines Compounds

There are three parts in this dissertation:In the first part,our efforts were concentrated on the bifunctional salen ligands catalyzed asymmetric reactions.We have studied the bifunctional Zn(salen) catalyzed asymmetric alkynylation of aldehydes.With a salen ligand bearing a scecondary basic 1-piperdinylmethyl group at C₃ and C₃′,dual activation of the electrophile and nucleophile was found as mechanistically proposed.Much improved catalytic acitivity as well as stetroselectivity was observed.And then we have studied asymmetric cyanoformylation of aldehydes catalyzed by the bifunctional salen-Ti(OⁱPr)₄ complex produced in situ.Under 10 mol%catalyst in iPrOH/CH₂Cl₂ at -40℃,a variety of aromatic aldehydes were converted into the corresponding cyanohydrin ethyl carbonates up to 92%ee.A potential transition state based on the experimental results,which explain the origin of the asymmetric induction,has been presented.In part two of our dissertation a special vicinal diamines was synthesized by reductive cross coupling of nitrones with N-tert-butylsulfinyl imines.And then we have studied the diamines catalyzed asymmetric methylation of aromatic aldehydes. Under the optimized conditions,good reactivity and excellent enantioselectivity were obtained in the addition of Me₂Zn to aromatic aldehyde,the ee value was up to 98%.Next,we have studied vinical diamine catalyzed the addition of substituted aryl zinc reagents to substituted benzaldehydes.We got five couples of enantiomers,which ee values were between 72%and 95%.The recoverable catalyst on the addition of phenyl zinc reagent to 2-bromobenzaldehyde was investigated.PEG and wang's reisn were used to synthesize polymer-supported diamine.The results demonstrated that the soluble PEG-bound vinical diamine exhibited good catalytic acitivity and enantioselectivity at first time.But when the recovered catalyst was used,a sightly loss of acitivity and enantioselectivity was obversed.Unfortunately,the reisn-supported ligand in the asymmetric addition of phenylzinc reagent to aldehyde had no catalytic acitivity. Finally,we studied the Reformatsky reaction of N-butylsulfinyl imines.Further investigations into the optimization of the reaction conditions,such as reaction temperature,solvent and additive were processed,and 98:2 dr of product was obtained under the optimized conditions.The further study is underway.