| Research Abstract |
For the continuing prosperity of human society in the 21st century, it is essential to construct environmentally benign catalytic processes without byproducts and waste, directed toward organic synthesis. In the Scientific Research B, novel rhodium-catalyzed cross-coupling and cycloaddition reactions of ketenes with alkenes or alkynes have been developed, leading to efficient methods for construction of cyclopropanes, 2-pyridones, pyrimidine-2,4-diones, and furans, which constitute new and functional monomers and materials. On the other hand, we have made an important contribution to ruthenium chemistry by developing a lot of novel ruthenium-catalyzed reactions as well as creation of novel Ru (0) and Ru (II) monomers and clusters. Recently, we have succeeded in development of codimerization and cotrimerization reactions of different alkenes, and in the Scientific Research B, we found that our original ruthenium(0) complex, Ru(η^6-cot)(η^2-dmfm)_2 [cot =1,3,5-cyclooctatriene, dmfm = dimethyl fumarate], showed high catalytic activity for selective trimerization of ethylene to isohexenes. It seems that the reaction proceeds via normal and successive insertion of ethylene into an alkyl-ruthenium bond. However, the present reaction proceeded via ruthenacyclopentanes as a key intermediate, which was confirmed by the formation of unusual isohexenes (a branched cotrimer) in place of normal 1-hexene (a linear cotrimer) as well as deuterium-labeled experiments. Accordingly, the reactions developed in this Scientific Research B are all atom-economical and environmentally benign processes, which offer innovative methods for construction of ring compounds via an efficient formation of metallacyclic intermediates. As a result, this research contributes significantly to green sustainable chemistry (GSC) for organic synthesis in the 21st century.
|
