3,3‘-Diphosphoryl-1,1‘-bi-2-naphthol−Zn(II) Complexes as Conjugate Acid−Base Catalysts for Enantioselective Dialkylzinc Addition to Aldehydes
作者:Manabu Hatano、Takashi Miyamoto、Kazuaki Ishihara
DOI:10.1021/jo060908t
日期:2006.8.1
A highly enantioselective dialkylzinc (R22Zn) addition to a series of aromatic, aliphatic, and heteroaromatic aldehydes (5) was developed based on conjugate Lewis acid−Lewis base catalysis. Bifunctional BINOL ligands bearing phosphine oxides [P(O)R2] (7), phosphonates [P(O)(OR)2] (8 and 9), or phosphoramides [P(O)(NR2)2] (10) at the 3,3‘-positions were prepared by using a phospho-Fries rearrangement
基于共轭路易斯酸-路易斯碱催化,开发了对一系列芳族,脂族和杂芳族醛(5)的高对映选择性二烷基锌(R 2 2 Zn)。带有氧化膦[P(O)R 2 ](7),膦酸酯[P(O)(OR)2 ](8和9)或磷酰胺[P(O)(NR 2)2 ](10的双功能BINOL配体)通过使用磷酸化-弗里斯重排作为关键步骤来制备3,3'-位。NaphO-Zn(II)-R 2的配位中心以路易斯酸为底物上的羰基,并在3,3'-二磷酰基-BINOL-Zn(II)中以磷酰基(PO)为路易斯碱活化R 2 2 Zn(II)催化剂可以以高对映选择性(高达> 99%ee)促进碳-碳键的形成。通过X射线分析游离配体(7)和四核Zn(II)团簇(21)进行了机理研究,对Zn(II)配合物进行31 P NMR实验,在配体之间没有非线性效应(7))和苯甲醛的Et加合物,以及与某些手性或非手性Zn(II)配合物的化学计量反应,提出了一种包含单体活性中间体的过渡态组装体。