新型可回收高聚物负载手性配体在苯乙烯类化合物均相不对称双羟化反应中的催化性能研究

A New Recyclabe Polymer-bound Chiral Ligand for the Homogeneous Catalytic Asymmetric Dihydroxylation of Styrenes

在多聚磷酸和AlCl3存在下,邻苯二甲酸酐与对二氟苯中通过Friedel-Crafts反应环化,以60%的产率生成1,4-二氟蒽醌.在碱性条件下,聚乙二醇单甲醚(HO-OPEG-OMe)与1,4-二氟蒽醌进行亲核单取代反应生成中间体F-AQN-OPEG-OMe,产率88%.然后F-AQN-OPEG-OMe与奎尼丁的锂盐再进行亲核取代反应,以91.7%的产率得到新型手性配体QD-AQN-OPEG-OMe.QD-AQN-OPEG-OMe与OsO4原位配位生成的均相催化剂在4种苯乙烯类化合物的不对称双羟化反应中表现出高的立体选择性(80%～94%ee)和催化活性(产率88%～96%).催化活性和立体选择性与Sharpless手性配体(DHQD)2AQN相当.反应结束后,加入乙醚可使配体沉淀和回收,配体的回收率均在95%～97%之间.循环使用5次,催化剂的催化活性和立体选择性无明显改变.

In the presence of aluminum trichloride and polyphosphoric acid, phthalic anhydride reacted to 1, 4-difluorobezene via Friedel-Crafts and cyclization to deliver 1, 4-difluoroanthraquinone in a modified method, the yield was 60%. F-AQN-OPEG-OMe was obtained in 88% yield by nucleophilic mono-substituted by HO-OPEG-OMe and 1, 4-difluoroanthraquinone in basic medium. Then, QD-AQN-OPEG-OMe was synthesized in 91.7% yield by reaction of F-AQN-OPEG-OMe with the lithium salt of quinidine. The homogeneous catalyst that QD-AQN-OPEG-OMe complexed with osmium tetroxide in situ delivered high enantioselectivities (80%~94%ee) and catalytic reactivities (88%~96% yields) in asymmetric dihydroxylation of four styrenes, comparable to that of the homogeneous catalyst with Sharpless ligand (DHQD)_2AQN reported. This ligand was recovered almost by a simple filtration and reused for five cycles without obvious decreased enantioselectivities and catalytic activities, with 95%~97% recovery of ligand.