Activation of Small Polar Molecules by Environmentally Benign Transition Metal Catalysts

点击翻译按钮获取中文摘要

Since we have already found that among group 8-10 transition metal complexes, low-valent ruthenium complexes especially show high affinity to heteroatoms such as N, S, and O atoms, characteristic activation of small polar molecules by ruthenium catalysts was investigated. As a result, we have succeeded in developing the following novel ruthenium-catalyzed carbon-carbon and carbon-heteroatom bond forming reactions ; 1)highly regio- and stereoselective addition of sulfenamides to electron-deficient alkynes leading to polyfunctional alkenes, 2)formal [4+2] cycloaddition of alkynes with electron-deficient alkenes to cyclohexenedicarboxylates via isomerization of alkynes and successive Diels-Alder reaction, 3)reconstructive synthesis of 2-pyranones, cyclopentenes, and cyclohexenones via carbon-carbon bond cleavage of cyclobutenones, 4)[2+2+2] cocyclization of three different alkynes (dimethyl acetylenedicarboxylate, 1-decyne and 3-hexyne), 5)regio- and stereoselective codimerization of different alkenes (2-norbornenes with acrylic compounds, and dihydrofurans with α,β-unsaturated esters).In addition, we succeeded in preparation of various Ru(0) complexes via selective ligand displacement of Ru(η^6-1,3,5-cyclooctatriene)(η^2-dimethyl fumarate)_2 (1), which was originally synthesized in our laboratory in 1999. Further study revealed that the stoichiometric reaction of 1 with phenol gave novel Ru(II) phenolate complexes, while the reaction of 1 with water in the presence of 1,2-bis(diphenylphosphino)ethane (dppe) gave a novel chiral Ru(0) aqua complex, Ru(η^2-dppe)(η^2-dimethyl fumarate)_2(H_2O) (2). Optical resolution of rac-2 was successfully performed by HPLC equipped with a chiral column. On the basis of the VT NMR data and DFT study, the behavior of the coordinated water (rotation and inversion) was disclosed.