Silver-Catalyzed Controlled Intermolecular Cross-Coupling of Silyl Enol Ethers: Scalable Access to 1,4-Diketones
Li Xu, Xiaoyi Liu, Gregory R. Alvey, Andrey Shatskiy, Jian-Quan Liu*, Markus D. Kärkäs* and Xiang-Shan Wang*
*Jiangsu Normal University, Xuzhou, Jiangsu 221116, China; KTH Royal Institute of Technology, SE-100 44 Stockholm, Sweden,
Email: liujq316
jsnu.edu.cn; karkaskth.se,
xswangjsnu.edu.cn
L. Xu, X. Liu, G. R. Alvey, A. Shatskiy, J.-Q. Liu, M. D. Kärkäs, X.-S. Wang, Org. Lett., 2022, 24, 4513-4518.
DOI: 10.1021/acs.orglett.2c01477
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Abstract
A silver-catalyzed controlled intermolecular cross-coupling of silyl enolates displays good functional group tolerance and allows efficient preparation of a series of synthetically useful 1,4-diketones. Preliminary mechanistic investigations suggest that the reaction proceeds through a one-electron process involving free radical species in which PhBr acts as the oxidant.
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proposed mechanism
Synthesis of 1-(4-Methoxyphenyl)-4-phenylbutane-1,4-dione
To a 10 mL Schlenk tube equipped with a magnetic stir bar was added ((1-(4-methoxyphenyl)vinyl)oxy)trimethylsilane (144.5 mg, 0.65 mmol), trimethyl((1-phenylvinyl)oxy)silane (96 mg, 0.5 mmol), CH3CN (2.0 mL), PhBr (157 mg, 1.0 mmol), and AgF (13 mg, 0.1 mmol). The reaction mixture was stirred at 25°C for about 6 h under argon. The resulting mixture was concentrated and the residue was taken up in ethyl acetate. The organic layer was washed with brine, dried over Na2SO4 and concentrated. Purification of the crude product by column chromatography (silica gel; petroleum ether/ethyl acetate 10:1) afforded the desired product in 69% yield (93 mg).
Synthesis of 1-Phenylpentane-1,4-dione
To a 10 mL dry Schlenk tube equipped with a magnetic stir bar was added trimethyl((1-phenylvinyl)oxy)silane (96.2 mg, 0.5 mmol), trimethyl(prop-1-en-2-yloxy)silane (195.4 mg, 1.5 mmol), CH3CN (2.0 mL), PhBr (157 mg, 1.0 mmol), and AgF (13 mg, 0.1 mmol). The reaction mixture was stirred at 25 °C for about 24 h under argon. The resulting mixture was concentrated and the residue was taken up in ethyl acetate. The organic layer was washed with brine, dried over Na2SO4 and concentrated. Purification of the crude product by column chromatography (silica gel; petroleum ether/ethyl acetate 13:1) afforded the desired product in 87% yield (76.7 mg).
Key Words
ID: J54-Y2022
