双噁唑啉接枝的氨基酸聚合物作为手性催化中心在不对称Henry反应中的应用

Application of Bisoxazoline-grafted Amino Acid Polymer as Chiral Catalytic Center in Asymmetric Henry Reaction

通过控制聚合单体L-谷氨酸-γ-乙酯和DL-半胱氨酸以及聚合过程中引发剂与单体的比例,制备了一系列溶解性能不同的氨基酸聚合物.利用其作为负载手性配体的载体,通过双噁唑啉配体上的双键和聚合物上巯基的加成反应,合成了一系列双噁唑啉接枝氨基酸聚合物.将合成的聚合物作为可回收的手性催化剂用于催化不对称Henry反应,反应选择性(e.e.值)在50%~90%之间,产率在67%~95%之间.该催化剂可以循环使用至少7次而不需要经过重新活化.

A series of amino acid polymers with different solubility was prepared through controlling the ratio of L-Glutamic acid-1-ethyl ester to DL-cysteine and the ratio of initiator to monomer in the polymerization process.With the amino acicl polymer as carriers for chiral ligands,a series of bisoxazoline-grafted amino acid polymers was synthesized by the addition reaction between the double bond on the bisoxazoline ligand and the sulfhydryl group on the polymer.The polymers can be used as a recoverable chiral ligand to catalyze asymmetric Henry reaction.The enantiomeric excess(e.e.)value of the reaction is between 50%—90%and the yield is between 67%—95%.The catalyst can be recycled for at least 7 times without reactivation.