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Synlett 2018; 29(04): 463-466
DOI: 10.1055/s-0036-1589135
DOI: 10.1055/s-0036-1589135
letter
Cu(I)-Catalyzed Synthesis of β,γ-Unsaturated Amides
Autoren
Financial support of this research by the College of the Holy Cross Summer Research Fellowship Program is gratefully acknowledged.
Weitere Informationen
Publikationsverlauf
Received: 31. August 2017
Accepted after revision: 24. Oktober 2017
Publikationsdatum:
22. November 2017 (online)
Abstract
Readily available propargyl alcohols were found to be useful substrates for the copper(I)-catalyzed synthesis of β,γ-unsaturated amides. Nucleophilic attack by the alcohol on the in situ generated ketenimine followed by base-catalyzed elimination and subsequent ring opening yields the desired products under mild conditions.
Supporting Information
- Supporting information for this article is available online at http://doi.org/10.1055/s-0036-1589135.
- Supporting Information (PDF) (opens in new window)
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References and Notes
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- 14 To a solution of propargyl alcohol 1a (119 mg, 0.96 mmol, 1.2 equiv) in CH2Cl2 (4.8 mL, 0.2 M) in a 1 dram vial was added tosyl azide (158 mg, 0.8 mmol, 1 equiv), then CuCl (16 mg, 0.16 mmol, 0.2 equiv) followed by Et3N (167 μL, 1.2 mmol, 1.5 equiv). The reaction was allowed to stir at ambient temperature in a block for 12 h at which time TLC analysis indicated complete consumption of the starting material and formation of the β,γ-unsaturated amide. The reaction was filtered through Celite. The solvent was removed in vacuo, and the residue was purified by flash column chromatography (hexanes/ethyl acetate = 5:1) to yield β,γ-unsaturated amide 2a (234 mg, 70%) as a white solid, mp 94–95 °C. The spectral data was in agreement with reported data.13 1H NMR (400 MHz, CDCl3): δ = 8.22 (s, 1 H), 7.93 (d, J = 8.4 Hz, 2 H), 7.33 (d, J = 8.4 Hz, 2 H), 5.61 (s, 1 H), 2.87 (s, 2 H), 2.44 (s, 3 H), 2.03 (m, 2 H), 1.79 (m, 2 H), 1.60–1.52 (m, 4 H). 13C NMR (100 MHz, CDCl3): δ = 168.8, 145.1, 135.4, 131.0, 129.5, 128.6, 128.4, 46.5, 28.1, 25.3, 22.4, 21.7, 21.6.