The Synthesis Of Organophosphine-Tungstophoric Compound Supported Primary-Amine Catalysts Derived From Cinchona Alkaloid And Their Application In Asymmetric Aldol Reaction

In this paper, a series of phosphine tungstophoric compound-supported primary-amine organocatalysts (2a～2c,2b’,2b1～2b3,3b1～3b3,4b) had been prepared through the radical addition of sulfydryl in HS(CH2)nPO(OC2H5)2(n=2,4,6) to 9-amino-9-deoxy-epi-cinchonidine/quinine, hydrolysis of ethyl phosphates (la-lc and lb’) and direct precipitation of -PO3H2 with Na2WO4·2H2O.These hosphine tungstophoric compound-supported primary-amine organocatalysts were comprehensively characterized by NMR, FT-IR, N2 adsorption and desorption, TG-DSC, ICP, HRTEM, XRD, elemental analysis and acid titration analysis, and their chemical composition, porous structure and surface morphology had been ascertained.Using the model asymmetric aldol reaction of cyclohexanone to 4-nitrobenzalde-hyde, aluminium phosphotungstate-supported primary-amine organocatalyst 3b2 prov-ed to be the best supported organocatalyst possessing excellent catalytic performances, and the optimal catalytic conditions such as 4-nitrobenzaldehyde (30.2 mg,0.2 mmol), cyclohexanone (0.5 mL), H2O (1.0 mL),3b2 (40 mg,5.7 mol%),15℃ and 72 h were screened out. Under these optimal conditions, the aldol reaction of various substituted benzaldehydes with cyclohexanone afforded 20～98% yield,82.2～96.3% ee anti and anti/syn=74-98/26-2. After the completion of reaction, supported catalysts 3b2 could be recovered by filtration from reaction mixture, and its steroselectivities significantly declined after the recovered 3b2 was reused seven times.