Synlett 2017; 28(16): 2135-2138
DOI: 10.1055/s-0036-1588874
letter
© Georg Thieme Verlag Stuttgart · New York

Palladium-Catalyzed Regioselective Hydroarylation of Ynamides with Aryl Iodides: Easy Synthesis of Various Substituted Enamides Containing Stilbene Derivatives

Hideaki Wakamatsu*
Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Komatsushima 4-4-1, Aoba-ku, Sendai 981-8558, Japan   Email: [email protected]   Email: [email protected]
,
Rika Yanagisawa
Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Komatsushima 4-4-1, Aoba-ku, Sendai 981-8558, Japan   Email: [email protected]   Email: [email protected]
,
Sho Kimura
Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Komatsushima 4-4-1, Aoba-ku, Sendai 981-8558, Japan   Email: [email protected]   Email: [email protected]
,
Nao Osawa
Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Komatsushima 4-4-1, Aoba-ku, Sendai 981-8558, Japan   Email: [email protected]   Email: [email protected]
,
Yoshihiro Natori
Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Komatsushima 4-4-1, Aoba-ku, Sendai 981-8558, Japan   Email: [email protected]   Email: [email protected]
,
Yuichi Yoshimura*
Faculty of Pharmaceutical Sciences, Tohoku Medical and Pharmaceutical University, Komatsushima 4-4-1, Aoba-ku, Sendai 981-8558, Japan   Email: [email protected]   Email: [email protected]
› Author Affiliations
Further Information

Publication History

Received: 20 April 2017

Accepted after revision: 19 May 2017

Publication Date:
06 July 2017 (online)


Abstract

Palladium-catalyzed hydroarylation of ynamides has been developed. The desired coupling products were obtained in good yields and with high regioselectivities. Various aryl iodides can be used in this reaction, permitting the syntheses of many different kinds of enamides from ynamides.

Supporting Information

 
  • References and Notes


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  • 10 Ethyl 4-[(1Z)-1-{Benzyl[(4-tolyl)sulfonyl]amino}oct-1-en-1-yl]benzoate (3a) and Ethyl 4-[(E)-2-{Benzyl[(4-tolyl)sulfonyl]amino}-1-hexylvinyl]benzoate (4a); Typical Procedure Ethyl 4-iodobenzoate (2a; 0.21 mL, 1.23 mmol, 3.0 equiv) was added a solution of ynamide 1a (150.0 mg, 0.41 mmol), Pd(OAc)2 (4.6 mg, 20.5 μmol, 5 mol%), DPPF (11.4 mg, 20.5 μmol, 5 mol%), and HCO2NH4 (77.6 mg, 1.23 mmol, 3.0 equiv) in DMF (20 mL) at 0 °C under argon. The mixture was stirred at 100 °C for 18 h and then cooled to 0 °C. H2O (22 mL) was added, and the aqueous phase was extracted with Et2O (3 × 50 mL). The organic phases were combined, washed with brine (1 × 50 mL), and dried (Na2SO4). The volatiles were removed under reduce pressure, and the residue was purified by column chromatography [silica gel, hexane–Et2O (20:1) to hexane–EtOAc (10:1)] to afford 3a, 4a, and recovered 1a (6.0 mg; 4%). 3a: off-white solid; yield: 161.1 mg (76%); mp 71 °C. IR (KBr): 3059, 2921, 1705, 1605 cm–1. 1H NMR (400 MHz, CDCl3): δ = 0.88 (t, J = 7.2 Hz, 3 H), 1.04–1.28 (m, 8 H), 1.38 (t, J = 7.2 Hz, 3 H), 1.92 (br s, 2 H), 2.48 (s, 3 H), 4.14 (br s, 1 H), 4.36 (q, J = 7.2 Hz, 2 H), 4.71 (br s, 1 H), 6.11 (t, J = 7.4 Hz, 1 H), 7.06–7.12 (m, 4 H), 7.21–7.23 (m, 3 H), 7.35 (d, J = 7.6 Hz, 2 H), 7.81–7.85 (m, 4 H). 13C NMR (100 MHz, CDCl3): δ = 14.0, 14.3, 21.5, 22.5, 28.7, 29.1, 29.9, 31.6, 52.4, 60.9, 126.4, 127.6, 128.0, 128.2, 129.3, 129.5, 129.5, 129.7, 134.6, 135.5, 137.3, 137.9, 141.7, 143.6, 166.2. EI-LRMS: m/z = 519 [M+], 364, 155, 91. EI-HRMS; m/z [M+] calcd for C31H37NO4S: 519.2443; found: 519.2442. 4a: off-white solid; yield: 31.9 mg (15%); mp 73–74 °C. IR (KBr): 2929, 1716, 1607 cm–1. 1H NMR (400 MHz, CDCl3): δ = 0.65–0.75 (m, 2 H), 0.81 (t, J = 7.2 Hz, 3 H), 0.97–1.05 (m, 4 H), 1.10–1.18 (m, 2 H), 1.38 (t, J = 7.2 Hz, 3 H), 2.42–2.49 (m, 2 H), 2.44 (s, 3 H), 4.25 (s, 2 H), 4.36 (q, J = 7.2 Hz, 2 H), 5.32 (s, 1 H), 7.17 (d, J = 8.2 Hz, 2 H), 7.26–7.35 (m, 7 H), 7.70 (d, J = 8.2 Hz, 2 H), 7.95 (d, J = 8.2 Hz, 2 H). 13C NMR (100 MHz, CDCl3): δ = 14.0, 14.3, 21.5, 22.5, 27.2, 29.3, 29.8, 31.5, 55.2, 60.9, 123.7, 126.8, 127.6, 127.9, 128.4, 129.3, 129.5, 129.7, 129.7, 134.7, 135.5, 143.7, 144.0, 149.2, 166.3. EI-LRMS: m/z: 519 [M+], 364, 155, 91. EI-HRMS: m/z [M+] calcd for C31H37NO4S: 519.2443; found: 519.2423