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Indium Triflate-Catalyzed Vinylation of β-Ketoesters with Acetylene Gas

Masaharu Nakamura, Kohei Endo and Eiichi Nakamura*

*Department of Chemistry, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan, Email: nakamurachem.s.u-tokyo.ac.jp

M. Nakamura, K. Endo, E. Nakamura, Org. Lett., 2005, 7, 3279-3281.

DOI: 10.1021/ol051057z


Abstract

α-Vinylated ketoester are atom-economically produced by an In(OTf)3-catalyzed addition of β-ketoesters to welding-grade acetylene in the presence of molecular sieves under solvent-free conditions in good to excellent yield.

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Details

The document discusses a study on the In(OTf)3-catalyzed vinylation of β-ketoesters with acetylene gas. The reaction, conducted under solvent-free conditions and using welding-grade acetylene, produces α-vinylated ketoesters in good to excellent yields. The process is practical and efficient, overcoming challenges associated with the gaseous nature and sensitivity of acetylene. The study found that using molecular sieves (MS) as additives significantly improved yields by acting as acid and water scavengers. Various β-ketoesters were tested, and the optimal conditions involved heating the mixture at 100°C under an acetylene atmosphere. The reaction was effective for both purified and welding-grade acetylene, with yields reaching up to 95%. The method also tolerated acid-sensitive groups and was applicable to substituted acetylenes. The research provides a practical approach for the synthetic utilization of acetylene gas, with potential applications in further synthetic elaboration of α-vinyl carbonyl compounds. The study was supported by the Ministry of Education, Culture, Sports, Science, and Technology of Japan, and detailed experimental procedures and spectral data are available online.


Indium-Catalyzed 2-Alkenylation of 1,3-Dicarbonyl Compounds with Unactivated Alkynes

K. Endo, T. Hatakeyama, M. Nakamura, E. Nakamura, J. Am. Chem. Soc., 2007, 129, 5264-5271.

Stereoselective Synthesis of Trisubstituted E-Iodoalkenes by Indium-Catalyzed syn-Addition of 1,3-Dicarbonyl Compounds to 1-Iodoalkynes

H. Tsuji, T. Fujimoto, K. Endo, M. Nakamura, E. Nakamura, Org. Lett., 2008, 10, 1219-1221.


Key Words

vinylation, active methylenes


ID: J54-Y2005-930