Synlett 2017; 28(03): 343-346
DOI: 10.1055/s-0036-1588097
letter
© Georg Thieme Verlag Stuttgart · New York

Cobalt(II)-Catalyzed Oxidative Coupling of Aromatic Tertiary Amines with Enol Silyl Ethers Leading to β-Aminoketone Derivatives

Norio Sakai*
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan   Email: sakachem@rs.noda.tus.ac.jp
,
Takuya Muraoka
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan   Email: sakachem@rs.noda.tus.ac.jp
,
Shun Matsumoto
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan   Email: sakachem@rs.noda.tus.ac.jp
,
Akihiro Mutsuro
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan   Email: sakachem@rs.noda.tus.ac.jp
,
Yohei Ogiwara
Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan   Email: sakachem@rs.noda.tus.ac.jp
› Author Affiliations
Further Information

Publication History

Received: 04 September 2016

Accepted after revision: 23 October 2016

Publication Date:
11 November 2016 (online)


Abstract

We demonstrated that a cobalt(II)-TBHP (tert-butyl hydro­peroxide) oxidizing system efficiently catalyzes the coupling of aromatic tertiary amines with enol silyl ethers, producing the corresponding β-aminoketones.

Supporting Information

 
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  • 11 General Procedure for a Cobalt-Catalyzed Oxidative Coupling of Aromatic Tertiary Amines with Enol Silyl Ethers To a screw-capped test tube (5 mL) under ambient atmosphere containing freshly distilled MeCN (0.5 mL) were successively added 0.5 M MeCN solution of CoBr2 (50 μL, 0.025 mmol), aniline (1.0 mmol), enol silyl ether (0.50 mmol), and 5.5 M tert-butyl hydroperoxide in decane (136 μL, 0.750 mmol). After the tube was sealed with a cap that contained a PTFE septum, the mixture was heated at 40 °C (bath temperature) and monitored by GC and TLC analysis. The reaction was quenched with a Na2CO3 aq solution (5 mL). The aqueous layer was extracted with CHCl3, the organic phases were dried over anhydrous Na2SO4, filtered, and evaporated under reduced pressure. The crude product was purified by silica chromatography (hexane–EtOAc = 4:1) to give the corresponding β-aminoketone. (3-Methylphenylamino)-1-phenyl-1propanone (1) White solid; 75% (90 mg). 1H NMR (300 MHz, CDCl3): δ = 8.00–8.02 (m, 2 H), 7.64–7.51 (m, 3 H), 7.37–7.31 (m, 2 H), 6.85–6.79 (m, 3 H), 3.95–3.90 (t, J = 6.9 Hz, 2 H), 3.34–3.30 (t, J = 6.9 Hz, 2 H), 3.01 (s, 3 H). 13C NMR (75 MHz, CDCl3): δ = 199.4, 148.5, 136.8, 133.1, 129.3, 128.6, 128.0, 116.5, 112.3, 47.9, 38.5, 35.1. MS (EI): m/z (%) = 239 (100) [M+].

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