茂钛Lewis-Bronsted 酸协同催化酯化/酰胺化反应

A serious new Lewis-Br?nsted acid titanocene complexes will be designed using Cp2TiCl2 as the start materials and sulfonic derivatives with O-hydroxycarboxylic groups of benzene as ligands. In the complex structures, O-hydroxyl and carboxyl groups will be acted as a bridge to coordinate with Ti atom, and titanocene will be as a frame and sulfonic group as a uint of Br?nsted acid in them. Based on the thought that the acidity of Lewis acid depends on the density of the central metallic atom, the acidity of titanocene Lewis acid will be controlled by the Br?nsted acid in molecule itself when tuned the quantity and the position of sulfonic group of the benzene ring as the constant of titanocene species. To further evidence this opinion, the intramolecular cooperative effect between Lewis acid and Br?nsted acid will be revealed through the exploration of the catalytic activation of complexes in this case. Then, a series of reactions will be investigated, such as esterification, interesterification and amidation of alcohols, phenols and amine dierivatives, respectively, when utilized the synthesized titanocene complexes as catalysts to active acid anhydrides or esters. To be the great expectation, a new multi-acid catalysis system of the intramolecular Lewis-Br?nsted acid will be proposed to understand the relationship between these titanocene complex structures and their properties, to reveal the difference of the catalytical behavior in three different reactions, to broaden the research field of the Lewis-Br?nsted acid chemistry and to push the appliation of the interesterification or amidation in this proposal.

以Cp2TiCl2为原料，以苯环上具有相邻羟基和羧基为基本结构单元的磺酸衍生物为配体，构建以相邻羟基和羧基的苯环结构为桥梁、以二茂钛为Lewis酸骨架中心、以磺酸基为Br?nsted酸基本单元的二茂钛Lewis-Br?nsted酸配合物。基于Lewis酸性中心原子的电子密度决定其强度的策略，保持二茂钛结构单元不变，调节强吸电子作用的磺酸基个数与位置，实现分子内Br?nsted酸对Lewis酸中心酸性强度的调控；通过相应配合物催化活性检测，揭示Br?nsted酸与Lewis酸的协同作用机制。再以配合物为催化剂，以酯化/酰胺化反应为模型，以酸酐或酯为活化对象，考察醇、酚和胺的酯化、酯交换及酰胺化反应，关联结构与催化性能间的关系，揭示催化剂对催化三类反应的差异性，建立分子内Lewis-Br?nsted酸的多酸催化新体系，丰富Lewis及Br?nsted酸催化化学，推进酯化/酰胺化反应实际应用。

本项目聚焦于茂钛Lewis-Brønsted酸协同催化体系的构建及其在缩合反应中的应用研究，取得了一些富有特色的研究成果，主要包括：（1）合成了8个茂钛Lewis-Brønsted酸金属有机配合物，其中6个得到单晶结构；（2）利用原位Vis-UV，1H NMR，ESI-MS等分析手段，研究了形成茂钛配合物的结构演化过程，为进一步应用于催化酯化∕酰胺化等缩合反应提供了支持；（3）基于茂钛Lewis-Brønsted酸配合物的基本架构，成功构建了9种茂钛Lewis-Brønsted酸催化体系，并发现了Brønsted酸配体对催化反应具有调节作用；进一步研究表明，茂钛Lewis-Brønsted酸催化体系不仅实现了传统酯化反应和酰胺化反应的转化，而且对更具挑战性的Mannich反应也取得了突破，同时还拓展了其在水相与多相的运用，解决了传统Lewis酸催化剂不耐水、稳定性差的难题；（4）利用多种原位实验技术在线监测了茂钛Lewis-Brønsted酸催化反应过程，揭示了催化剂与反应的本构关系，证实了分子内茂钛Lewis-Brønsted酸的协同活化作用是实施高效催化的根本所在，并由此凝练出茂钛Lewis-Brønsted酸的协同催化理论模型，这不仅为Lewis酸催化化学提供了一种有效范式，而且为有机合成方法学也增添了新的内容。项目执行期间，共发表SCI源刊学术论文15篇（其中2014年发表于Chem. Eur. J. 杂志的文章被选作亮点工作进行了介绍），发表会议论文10篇，获得授权发明专利8件，受邀作国内口头会议报告4次，培养博士研究生2名、硕士研究生8名。