Study On The Asymmetric Synthesis Catalyzed By The Rare Earth Metal Compounds With Phenoxy-Functionalized Chiral Prolinols

Several salicylaldehydes were synthesized from the reaction of different phenols with paraformaldehyde.Then different salicylaldehydes react with chiral prolinol give four corresponding phenoxy-functionalized chiral prolinol compounds.The catalytic properties of rare earth metal amlides with chiral prolinol compounds were examined in the asymmetric hydrophonylation of unsaturated amides,andthe possible mechanism was verified.Furthermore,a mononuclear chiral ytterbium complex from the reaction of rare earth metal amide with phenoxy-functionalized of chiral prolinol was synthesized andthe catalytic performance in asymmetric reduction of unsaturated ketones was investigated successfully.1.Asymmetric hydrophosphonylation of unsaturated amides catalyzed by RE[N(TMS)2]3(μ-Cl)Li(THF)3 with phenoxy-functionalized chiral prolinolsRare earth metal amides RE[N(TMS)2]3(μ-C1)Li(THF)3(Ln = Yb,Y,La,Lu,Sc)with phenoxy-functionalized chiral prolinols catalyzes asymmetric hydrophosphonylation of unsaturated amides in mild conditions smoothly.With 10 mol%catalyst loading and 20 mol%chiral proligand H2L2((S)-2-((2-(hydroxydiphenylmethyl)pyrrolidin--yl)methyl)-4,6-bis(2-phenyl-propan-2-yl)phenol,the reactions complete at room temperature in 12 h with excellent yield(83%-99%)and good enantioselectivity(61%-89%).The absolute configuration of the product was determined by means of cultivating single crystal and X-ray diffraction.Besides,attemption to verify the active intermediate in the catalytic system,to magnify the reaction to gram scale and to test whether there is an asymmetric amplification effect in the current catalytic system were also examined.2.Asymmetric reduction of a,β-unsaturated ketones catalyzed by chiral rare earth metal complexesA new mononuclear chiral ytterbium complex[L1Yb(L1H)](L1=(2,4-di-tert-butyl-6-(((S)-2-(hydroxydiphenylmethyl)pyrrolidin-l-yl)methyl)phenol)was successfully synthesized with the treatment of the ytterbium amide with chiral prolinol compound according to the previous work.The complex[L1Yb(L1H)1 catalyzes the asymmetric reduction of α,β-unsaturated ketones successfully with 10 mol%catalyst loading,1.2 equivalent HBpin as reducing agent,at-40°C for 24 h.The model reaction can obtain chiral allyl alcohol with 99%yield and 83%ee.The catalytic system can apply to a series of substates include the unsaturated ketones bearing both electron-withdrawing and electron-donating groups with excellent yields(up to 99%)and good enantioselectivitoes(up to 89%).The reaction system is relative simple,safty and high performance.