| Co-Investigator(Kenkyū-buntansha) |
URA Yasuyuki Kyoto Univ., Graduate School of Eng., Instructor, 工学研究科, 助手 (40335196)
WADA Kenji Kyoto Univ., Graduate School of Eng., Lecturer, 工学研究科, 講師 (10243049)
KONDO Teruyuki Kyoto Univ., Graduate School of Eng., Associate Professor, 工学研究科, 助教授 (20211914)
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| Research Abstract |
The formation of metal-heteroatom bond formation is important as a key step for developing novel catalytic heterofunctionalization of unsaturated compounds. In this study, we paid our attention to the formation of ruthenium-hetero atom bond, and the following novel ruthenium-catalyzed reactions have been developed. First, we found that low-valent ruthenium complexes with a π-acidic ligand, such as Ru(η^6-cot)(dmfm)_2 [cot = 1,3,5-cyclooctatriene, dmfm = dimethyl fumarate] and Ru_3(CO)_<12>, are highly active catalysts for the intramolecular hydroamination of aminoalkynes. The reaction is highly regioselective, and a nitrogen atom is selectively attached to an internal carbon of alkynes to give five-, six-, and seven-membered nitrogen heterocycles as well as indoles in good to high yields. Second, we showed that [RuCl_2(CO)_3]_2ldppp [dppp = 1,3-bis(diphenylphosphino)propane] was a highly effective catalyst system for the first intramolecular oxidative amination of a variety of aminoalk
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enes when it was used concomitantly with K_2CO_3 and allyl acetate in N-methylpiperidine, to give the corresponding cyclic imines and indoles in excellent yields. Futhermore, a new and highly efficient catalytic system based on CpRuClL_2 is proposed for the S-propargylation of thiols by propargyl carbonates under neutral conditions, in which specific requirements inherent to the different reactivities of aliphatic and aromatic thiols are achieved by tuning both the nature of thee ancillary ligand L and experimental conditions.. On the other hand, sulfenamides smoothly add to electron-deficient alkynes by [RuCl_2(CO)_3]_2 or Ru_3(CO)_<12> catalyst to give the corresponding polyfunctional alkenes in high yield with high regio-and stereoselectivity (Z 100%).
Recently, we have also reported the novel zerovalent ruthenium complex Ru(η_6-cot)(dmfm)2, which showed high catalytic activity in a unique dimerization of 2,5 norbornadiene to novel half-cage compounds, PCTD [pentacyclo[6.6.0.0^<2,6> 0^<3,13> 0^<10,14>]tetradeca-4,11-diene]. During our further investigation of the reactivity of this complex, we found that the reaction with p-quinones gave Ru(η^6-cot)(ρ-quinone) complexes and the reaction with arenes gave novel (η6-arene)Ru(dmfm)2 complex, as well as the formation of Ru(dmfm)2(N-N'-N") complexes by the reactions with tridentate pyridyl ligands such as 2,2':6',2"-terpyridine (N-N'-N"). All reactions proceeded via the direct ligand exchange reactions of cot andlor dmfm in Ru(η^6-cot)(dmfm)_2, and the new complexes prepared here can be expected as efficient catalysts for heterofunctionalization of unsaturated compounds. Less
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