Ruthenium-Catalyzed Intramolecular Oxidative Amination of Aminoalkenes Enables Rapid Synthesis of Cyclic Imines
Teruyuki Kondo, Takumi Okada and Take-aki Mitsudo*
*Department of Energy and Hydrocarbon Chemistry, Graduate School of
Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan, Email: mitsudoscl.kyoto-u.ac.jp
T. Kondo, T. Okada, T.-A. Mitsudo, J. Am. Chem. Soc., 2002, 124, 186-187.
DOI: 10.1021/ja017012k
Abstract
[RuCl2(CO)3]2/dppp is a highly effective catalyst system for the intramolecular oxidative amination of various aminoalkenes in presence of K2CO3 and allyl acetate in N-methylpiperidine to give the corresponding cyclic imines and indoles in excellent yields.
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Details
The document discusses the development of a ruthenium-catalyzed intramolecular oxidative amination of aminoalkenes to synthesize cyclic imines. This method offers a valuable alternative to the more challenging cyclization of aminoalkenes and the expensive use of aminoalkynes. The researchers, Teruyuki Kondo, Takumi Okada, and Take-aki Mitsudo from Kyoto University, found that a catalyst system comprising [RuCl2(CO)3]2/dppp, K2CO3, and allyl acetate in N-methylpiperidine is highly effective for this transformation. The study highlights the importance of solvent and ligand choice, with N-methylpiperidine and dppp proving to be the most effective. The reaction conditions were optimized to achieve high yields of cyclic imines, with the best results obtained at 140°C for 8 hours. The mechanism involves the coordination and oxidative addition of the amine functionality to a ruthenium center, followed by alkene insertion and reductive elimination. This process is regioselective and can form five- and six-membered cyclic imines. The research provides a practical and efficient method for synthesizing unsaturated nitrogen heterocycles, supported by a grant from the Japan Society for the Promotion of Science.
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ID: J48-Y2002-1000