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DOI: 10.1055/s-2006-933110
Au(I)-Catalyzed Cyclization of tert-Butyl Carbonates Derived from Homopropargyl Alcohols: A Catalytic Alternative to Cyclic Enol Carbonates
Publication History
Publication Date:
09 March 2006 (online)
Abstract
Au(I)-complexes catalyze cyclization of tert-butyl carbonates derived from a variety of homopropargyl alcohols. This procedure offers a catalytic alternative to stoichiometric Lewis acids for the preparation of a range of enol carbonates.
Key words
gold catalysis - tert-butyl carbonate - homopropargyl alcohol - enol carbonate - ligand
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References and Notes
The β-hydroxyketone 3a is formed during the reaction, not during the subsequent workup. For example, upon a long-term storage of 2a, there was no change in the spectral integrity or in its TLC profile.
10
Representative Procedure for the Cyclization of 1d into 2d.
To a solution of 1d (100 mg, 0.384 mmol) in 1,2-dichloro-ethane (2 mL) at 0 °C, was added Au(PAr3)Cl (Ar = C6F5) (14.3 mg, 19.2 µmol), followed by AgSbF6 (6.6 mg, 19.2 µmol). Upon addition of AgSbF6, the color of the reaction mixture immediately turned to orange. The reaction mixture was kept at 0 °C for 15 h, then was slowly allowed to warm to r.t. over 5 h. After the reaction was judged to be complete by TLC, the crude mixture was concentrated to ca. 0.5 mL and was loaded on silica gel column and was eluted with EtOAc-hexane (1:4) to obtain 62.8 mg (80%) of 2d as pale yellow oil, along with 5.7 mg (8%) of hydrolyzed by-product, 3d.
For compound 2a see ref. 2.
Compound 2b: IR: 1777 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.40 (d, J = 7.9 Hz, 2 H), 7.31 (d, J = 7.8 Hz, 2 H), 5.42 (dd, J = 3.3, 10.7 Hz, 1 H), 4.87 (dd, J = 1.5, 2.2 Hz, 1 H), 4.44 (app t, J = 1.8 Hz, 1 H), 2.93 (dd, J = 3.3, 15.4 Hz, 1 H), 2.76 (tdd, J = 1.5, 10.6, 15.4 Hz, 1 H). 13C NMR (100 MHz, CDCl3): δ = 150.8, 146.7, 135.9, 135.6, 129.9, 127.8, 95.8, 78.7, 33.8. MS (EI): m/z = 181 [M - CO2 + H].
Compound 2c: IR: 1779 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.33 (t, J = 7.7 Hz, 1 H), 6.94-6.88 (m, 3 H), 5.41 (dd, J = 3.3, 10.6 Hz, 1 H), 4.86 (app t, J = 1.8 Hz, 1 H), 4.42 (app t, J = 1.9 Hz, 1 H), 3.81 (s, 3 H), 2.93 (dd, J = 3.3, 15.4 Hz, 1 H), 2.79 (tdd, J = 1.9, 10.7, 15.4 Hz, 1 H). 13C NMR (100 MHz, CDCl3): δ = 160.0, 150.4, 146.3, 137.9, 130.0, 117.8, 114.7, 111.2, 94.8, 78.6, 55.3, 33.2.
Compound 2d: IR: 1780 cm-1. 1H NMR (400 MHz, CDCl3): δ = 7.35-7.25 (m, 1 H), 7.24-7.12 (m, 3 H), 5.40 (dd, J = 3.3, 10.3 Hz, 1 H), 4.85 (app t, J = 2.2 Hz, 1 H), 4.42 (app t, J = 1.8 Hz, 1 H), 2.92 (dd, J = 3.2, 15.0 Hz, 1 H), 2.79 (tdd, J = 1.4, 10.6, 15.4 Hz, 1 H), 2.39 (s, 3 H). 13C NMR 100 MHz, CDCl3): δ = 151.2, 147.1, 139.5, 137.1, 130.7, 129.5, 127.0, 123.4, 95.4, 79.5, 33.9, 22.1.
Compound 2e: IR: 1772 cm-1. 1H NMR (400 MHz, CDCl3): δ = 4.77 (app t, J = 1.8 Hz, 1 H), 4.36 (app t, J = 1.4 Hz, 1 H), 4.15 (ddd, J = 2.3, 6.9, 10.2 Hz, 1 H), 2.65 (dd, J = 2.9, 15.0 Hz, 1 H), 2.50 (tdd, J = 1.5, 10.3, 15.0 Hz, 1 H), 2.00 (m, 1 H), 1.85-1.07 (m, 10 H). 13C NMR (100 MHz, CDCl3): δ = 151.7, 147.4, 94.9, 82.6, 41.9, 29.1, 28.6, 28.4, 26.7, 26.3, 26.1.
Compound 2f: IR: 1772 cm-1. 1H NMR (400 MHz, CDCl3): δ = 4.79 (t, J = 1.5 Hz, 1 H), 4.44 (m, 1 H), 4.37 (t, J = 1.5 Hz, 1 H), 2.70 (dd, J = 3.3, 15.4 Hz, 1 H), 2.46 (tdd, J = 1.5, 9.5, 15.0 Hz, 1 H), 1.77 (m, 1 H), 1.75-1.38 (m, 3 H), 0.97 (t, J = 7.3 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 151.4, 147.3, 95.0, 78.3, 37.0, 31.5, 18.5, 14.3.
Compound 2g: IR: 1775 cm-1. 1H NMR (400 MHz, CDCl3): δ = 4.78 (t, J = 1.9 Hz, 1 H), 4.37 (t, J = 1.9 Hz, 1 H), 4.13 (ddd, J = 2.9, 6.6, 10.6 Hz, 1 H), 2.66 (dd, J = 3.0, 15.1 Hz, 1 H), 2.48 (tdd, J = 1.5, 10.6, 15.4 Hz, 1 H), 1.93 (m, 1 H), 1.05 (d, J = 7.0 Hz, 3 H), 0.99 (d, J = 7.0 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 151.6, 147.4, 94.9, 83.2, 32.5, 29.0, 18.2, 18.1.
Compound 2h: IR: 1772 cm-1. 1H NMR (400 MHz, CDCl3): δ = 4.77 (dd, J = 0.7, 2.6 Hz, 1 H), 4.39 (dd, J = 1.4, 2.6 Hz, 1 H), 3.90 (dd, J = 4.4, 7.3 Hz, 1 H), 2.68 (m, 1 H), 1.92-1.52 (m, 7 H), 1.21 (d, J = 6.9 Hz, 3 H), 1.45-1.10 (m, 4 H). 13C NMR (100 MHz, CDCl3): δ = 156.7, 147.3, 93.7, 87.2, 39.8, 32.0, 29.8, 26.6, 26.3, 14.5.
Compound 2i: IR: 1773 cm-1. 1H NMR (400 MHz, CDCl3): δ = 4.80 (dd, J = 1.1, 2.6 Hz, 1 H), 4.40 (dd, J = 1.5, 2.6 Hz, 1 H), 4.10 (dt, J = 4.0, 8.1 Hz, 1 H), 2.52 (m, 1 H), 1.75-1.47 (m, 3 H), 1.47-1.20 (m, 9 H), 1.23 (d, J = 7.0 Hz, 3 H), 0.88 (t, J = 7.0 Hz, 3 H). 13C NMR (100 MHz, CDCl3): δ = 156.6, 147.1, 93.8, 83.3, 34.7, 33.6, 32.4, 29.9, 29.7, 24.8, 23.3, 14.8, 14.3.