Citric Acid → (E)-2,3,5-trimethyl-6-(3-methylnon-2-enyl)-1,4-benzoquinone

関与物質

反応条件

反応手順

Zirconocene dichloride (220 mg, 0.755 mmol) was treated with trimethylaluminum in heptane (3 mL 2.0 M) and the solvent removed in vacuo. Dichloroethane (3 mL) was added and the yellow solution cooled to 0° C. prior to slow addition of 450 μL 1-octyne (336 mg, 3.05 mmol). The ice bath was removed after 20 minutes and the reaction warmed to rt over 2.5 h at which time it was concentrated in vacuo to a yellow slurry and triturated with hexanes (4 mL) and the solvent removed in vacuo. Hexanes (3 mL) was added and the liquid cannulated away from the white solids. The solids were washed with 2 mL hexanes and the washings combined, concentrated to a yellow oil, dissolved into THF (5 mL) and cooled to −78° C. 2-(chloromethyl)-3,5,6-trimethyl-1,4-benzoquinone (400 mg, 2.01 mmol) was dissolved into THF (3 mL) and transferred to the vinyl alane via cannula with THF (2×1 mL) to assist the transfer. bis-(Triphenylphosphine)nickel dichloride (66.2 mg, 0.101 mmol) was suspended in THF (2 mL) and treated with n-BuLi in hexanes (1.6 M, 0.20 mmol) to give a clear, blood red solution which was added via cannula to the chilled vinyl alane, chloromethyl quinone solution. The reaction was warmed to room temperature overnight and chilled to −20 C prior to addition of a 1 M citric acid solution (20 mL). The solution was stirred for 0.75 h, EtOAc (10 mL) added and the layers separated. The aqueous phase was extracted EtOAc (2×10 mL), the combined organics washed with brine (2×10 mL), dried over anhydrous Na2SO4 and concentrated to a yellow oil. Multiple flash chromatography yielded 138.7 mg (23.9%) of (E)-2,3,5-trimethyl-6-(3-methylnon-2-enyl)-1,4-benzoquinone as a yellow oil. 1H NMR (400 MHz, CDCl3) δ4.91 (t, J=6.8 Hz, 1H), 3.18 (d, J=6.8 Hz, 2H), 2.00 (s, 9H), 1.92 (t, J=8.0 Hz, 2H), 1.70 (s, 3H), 1.34-1.21 (m, 8H), 0.84 (t, J=6.8 Hz, 3H). 13C NMR (100 MHz, CDCl3) δ 187.8, 187.0, 143.2, 140.2, 137.4, 119.1, 39.6, 31.6, 28.8, 27.7, 25.5, 22.6, 16.1, 14.0, 12.3, 12.1

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