Synthesis and Application of Salen Complexes Supported on Poly(norbornene)s and Gold-Nanoparticles

不对称催化是合成手性化合物最有效的方法。虽然不对称催化转化在过去几年中变得越来越重要，但它们在工业中的实际应用是有限的。主要的限制是过渡金属催化剂的分离和再利用困难。对于一类重要的不对称转化，即手性金属-锰配合物对未官能化烯烃的环氧化反应，尤其如此。在乔治亚理工学院（美国亚特兰大）Marcus Weck教授的团队呆了一年的目的是开发(i)高活性和选择性和（ii）完全可重复使用的支持的salen催化剂。为了实现目标(1)，确保金属中心的良好可达性是很重要的。这将通过合成与可溶性载体（如聚降冰片烯）或金纳米粒子捆绑在一起的单功能化盐核来实现。这两种支持允许合成明确的，固定配合物与可控的金属负载。为了实现目标（ii），必须尽量减少环氧化反应过程中催化剂的降解。这将通过合成具有位点隔离金属中心和连接剂与salen核心之间稳定的C-C键连接的催化剂来实现。

Asymmetric catalysis is the most powerful method for the synthesis of chiral compounds. While asymmetric catalytic transformations have become more important in the last years, their use in practical applications in industry is limited. The primary restrictions are difficulties in separating and reusing the transition metal catalysts. This is especially true for an important class of asymmetric transformations, the epoxidation of unfunctionalized olefins by chiral metal-salen complexes based on manganese. The aim of the one-year stay in Professor Marcus Weck's group at the Georgia Institute of Technology (Atlanta, USA) is to develop (i) highly active and selektive and (ii) fully reusable supported salen catalysts. To accomplish goal (i) it is important to ensure a good accessibility to the metal centers. This will be achieved by synthesizing monofunctionalized salen-cores tethered to soluble supports such as poly(norbornene)s or gold nanoparticles. Both supports allow for the synthesis of welldefined, immobilized complexes with controllable metal loadings. To achieve goal (ii) degradation of the catalyst during the epoxidation reactions must be minimized. This will be realized by synthesizing catalysts with site-isolated metal centers and stable C-C bond linkages between the linker and the salen core.