膦手性化合物合成及其在查尔酮不对称加成反应中应用

Synthesis of chiral phosphines and application in asymmetric addition reaction of chalcone

以L-薄荷醇为手性拆分试剂通过苯基二氯化膦制备含有膦手性有机膦硼烷化合物,重结晶分离出两种构型产物,发现它们在1H-NMR图谱上有显著差异.利用所得到的单一构型产物在甲基锂作用下转化为构型保持的甲基取代手性膦硼烷化合物,X射线单晶衍射确定其分子结构.在过氧叔丁醇氧化剂存在下,手性有机膦化合物可进一步转化为手性氧化膦化合物,反应过程中膦手性构型得以很好保持.在优化反应条件下,有机膦化合物参与的二乙基锌与查尔酮的不对称加成反应,目标产物的最高收率为76%,对映选择性为9%.

Chiral phosphines-borane adducts are synthesized from dichlorophenylphosphine using L-menthol as a chiral resolution reagent.The two configurations of phosphines-borane adducts exhibit different chemical shifts in the 1H-NMR spectrum,and can be separated by recrystallization.The single enantiomer is methylated with MeLi to afford single configuration of chiral methylated phosphines-borane adduct with retention of configuration,and its molecular geometry is characterized by X-ray crystal structure analysis.Chiral phosphines are transformed into the corresponding chiral phosphine oxides with configuration retention using tert-butyl hydroperoxide(TBHP)as oxidant under certain conditions.In addition,the resultant chiral phosphine ligands are evaluated in the asymmetric addition of Et2Zn and chalcone,affording the corresponding compound with 76%yield,but a low enantioselectivity of 9%.