| This thesis aims at the study on the cyanosilylation of aldehyde,amines with trimethylsilylcyanide(TMSCN)promoted by Lewis acidic Mg(II).This dissertation consists of three parts as following:Chapter 1 reviewed the Lewis acid-catalyzed cyanosilylation of aldehydes with TMSCN and one-pot cyanosilylation of aldehydes or ketones,amines with TMSCN.The asymmetric cyanosilylation involved chiral amines and chiral catalysts was also summarized.In chapter 2,the cyanosilylation of aldehydes promoted by MgI2 etherate[MgI2·(OEt2)n]was investigated.Firstly,the catalytic effect of various magnesium halides was studied.Secondly,the catalytic amounts of MgI2 etherate and solvent-effect were further investigated,respectively.One-pot cyanosilylation of aldehydes or ketones,amines with trimethylsilylcyanide catalyzed by MgI2 etherate was developed.The results suggest(1)MgI2·(OEt2)n is effective to a variety of aldehydes such as aromatic,heteroaromatic,aliphatic and α,β-unsaturated aldehydes,which could smoothly afford the desired cyanohydrins in good to excellent yields.(2)MgI2 ·(OEt2)n-catalyzed cyanosilylation exhibits high chemoselectivity toward aldehydes in the presences of its parent aldimines.The crossover experiments suggests that aldehyde is firstly activated by MgI2 ·(OEt2).and affords cyanohydrins.This magnesium-catalyzed cyanosilylation is mild,efficient and operationally simple.Iodide counterion,weakly coordinating peripheral ethereal ligands for Mg(II),and a non-coordinating reaction media are critical factors for the unique reactivity of this catalytic system.In chapter 3,asymmetric cyanosilylation of aldehydes with chiral auxiliary amines promoted by MgI2 etherate was investigated.L-phenylglycinealcohol was proved to be the better chiral auxiliary amine according to its reactivity and stereoselectivity.The cyanosilylation of a variety of aldehydes with L-phenylglycinealcohol was studied.The primary results show good yields and excellent diastereoselectivity.The reactivity and stereoselectivity of aldehydes are subjected to its electronic effect of substitution group on the aromatic ring.And cyanosilylation reaction involved by L-phenylglycinealcohol could provide amino nitrile compounds with efficient and high stereoselectivity,which was utilized into the synthesis of drugs such as saxagliptin,bocepevir and Pril-type drugs. |
