Synthesis Of A Novel Type Of Zirconium Phosphonate-Supported Primary-Amine Catalysts Derived From Cinchona Alkaloid And Their Application In Asymmetric Aldol Reaction

In this paper, a series of various phosphonates had been synthesized by using cinchonidine as starting material by several steps:Michaelis-Arbuzor, nuclear substiation, Mistunobu, free radical addition and hydrolysis reaction. And zirconium phosphonate-supported primary amine catalysts with different organic arm lengths were prepared by the precipitation of various phosphonates with ZrOCl2 in AcOH/HCl medium.The structure, morphology and chemical composition of zirconium phosphonate-supported primary amine catalysts were characterized by IR, NMR, TG, XPRD, N2 adsorption and desorption isotherms and TEM.The synthesized various zirconium phosphonate-supported 9-amino-9-deoxy-epicinchonidine catalysts were applied in asymmetric Aldol reaction of benzaldehyde with cycloketone, and the optimum experimental conditions were screened in details. The anti-Aldol product in 97% yield, 4.5:1 dr and anti-95%ee was obtained at 20℃for 96 h in water (v=1mL),7c as catalyst (10 mol%) and TfOH (15 mol%) as additive. However, the good catalytic properties were obtained for benzaldehydes with electrondrawing substituents. After the reaction was completed, the supported catalyst was recovered and resued without the sharp loss of the catalytic activities for three times.