Development of Novel Heterogeneous Ruthenium Catalysts for Environmentally-benign Organic Transformations

开发对环境友好、原子效率高的新型固体催化剂是非常有必要的。本研究开发了CeO2或ZrO2担载的Ru催化剂，它们对稳定的芳香族C-H键的直接芳基化和烷基化反应、稳定的C-C键的裂解和重构的烯丙基转移反应、羧酸与炔烃的区域和立体选择性加成、不饱和烃的选择性交叉偶联以及通过氨基醇脱氢环化合成吲哚都是非常有效的。这些催化剂是可回收的，不会损失显著的活性，而且Ru物种在溶液中的浸出可以忽略不计。XAFS和FTIR等光谱研究表明，CeO_2表面形成了扭曲的Ru=O物种，它们将在原位转化为低价的活性Ru物种。

The development of novel solid catalysts effective for environmentally benign, highly atom-efficient organic transformations is highly desired. In the present study, CeO2-or ZrO2-supported ruthenium catalysts which are quite effective for the direct arylation and alkylation of stable aromatic C-H bond activation, the allyl transfer reactions via the cleavage and reconstruction of stable C-C bonds, the regio-and stereoselective addition of carboxylic acids to alkynes, the selective cross-coupling of unsaturated hydrocarbons, and the synthesis of indole via the dehydrogenative cyclization of an amino alcohol have been developed. These catalysts are recyclable without loss of significant activities, and the leaching of Ru species into solution is negligible. The spectroscopic studies, e. g. XAFS and FTIR studies, have revealed the formation of distorted Ru=O species on the surface of ceria, which would be transformed to low-valent active Ru species in situ.