Synthesis Of A Novel Type Of Zirconium Phosphonate-Supported Cinchona Alkaloid-derived Thiourea And Its Application In The Asymmetric Michael Addition Reaction

In this paper, a series of phosphonates with the different arm chain lengths had been synthesized by using quinine as starting material by several steps:Michaelis-Arbuzor, nuclear substation, Mistunobu, free radical addition and hydrolysis reaction. And zirconium phosphonate-supported quinine-derived thiourea organocatalysts with different arm chain lengths were prepared by the precipitation of various phosphonates with ZrOC12in methanol medium.The chemical composition, morphology and structure of supported quinine-derived thiourea organocatalysts were characterized by NMR, IR, TG, N2adsorption and desorption isotherms, SEM and TEM.The synthesized zirconium phosphonate-supported thiourea organocatalysts were applied in asymmetric Michael addition reactions of β-nitrostyrenes with1,3-diketones, and the optimum experimental conditions were screened out in detail. The Michael addition product was obtained in98.7%yield and85.4%e.e.at20℃for44h in DCM (v=1mL) using7b as catalyst (5mol%). However, the good catalytic properties were obtained for β-nitrostyrenes with o-position electrondrawing substituents. After com-pleting the reaction, the zirconium phosphonate-supported thiourea organocatalysts could be readily recovered in quantitative yield by centrifugation or filtration, and used for three consecutive runs without the significant loss in catalytic performance.