To Probe the Origin of Activation Effect of Carboxylic Acid and (+)-NLE in Tridentated Titanium Catalyst Systems

The activation effect of carboxylic acid and positive nonlinear effect ((+)-NLE) in tridentated titanium catalyst systems for hetero Diels−Alder reaction and aldol-type reactions has been first elucidated on the basis of X-ray crystal structural analysis of homochiral (pseudo-octahedral coordination geometry with C2 symmetry) and heterochiral (pseudo-octahedral coordination geometry with C1 symmetry) titanium complexes and the observation of their different reactivities with carboxylic acid additive.

针对用于杂狄尔斯-阿尔德反应（hetero Diels−Alder reaction）与羟醛型反应（aldol-type reactions）的三齿钛催化剂（tridentated titanium catalyst）体系，羧酸的活化效应与正非线性效应((+)-NLE)已通过两项途径首次得到阐明：一是对同手性（具有C₂对称性的拟八面体配位几何构型）与异手性（具有C₁对称性的拟八面体配位几何构型）钛配合物（titanium complexes）的X射线晶体结构分析（X-ray crystal structural analysis），二是对其与羧酸添加剂间反应活性差异的观测。