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设计、合成了一种新型的三氮唑桥连吡啶盐聚L-亮氨酸Juli-Colonna反应催化剂QC-1,在查尔酮类化合物的不对称环氧化反应中可以同时兼作手性催化剂和相转移催化剂,显示了理想的催化活性、立体选择性和底物普适性。反应对多种查尔酮类底物均可获得高的对映选择性,最高达98%e.e.,尤其是对邻位取代苯基查尔酮类化合物的不对称环氧化亦可实现85%~90%e.e.;反应速度快、催化剂用量可显著减少,当催化剂用量减至1 mol%时,对查尔酮的环氧化仍可以85%的收率和90%e.e.获得目标产物。同时,通过此种结构修饰,改善了催化剂的性状,粉末状的催化剂易回收,且在循环使用中保持催化活性,解决了催化剂的回收、再利用问题,具有潜在的工业化应用前景。
A new type of Juli-Colonna catalyst, QC-1, which is a novel pyridinium salt of poly (L-leucine) bridged with diazoxide, was designed and synthesized. Asymmetric epoxidation of chalcones with chiral Catalysts and phase transfer catalysts show the desired catalytic activity, stereoselectivity and substrate universality. The reaction achieves high enantioselectivities up to 98% ee for a wide range of chalcones, especially for the asymmetric epoxidation of o-substituted phenylchalcones 85% ~ 90% ee; the reaction rate is fast, the amount of catalyst can be significantly reduced, and when the amount of catalyst is reduced to 1 mol%, the target product can still be obtained in 85% yield and 90% ee for epoxidation of chalcone. At the same time, the structure modification improves the properties of the catalyst, the powdery catalyst is easy to be recycled, the catalyst activity is maintained during the recycling, the problem of recovery and reuse of the catalyst is solved, and the potential industrialized application prospect is obtained.