Sodium Carbonate → Ethyl 2-[2-(4'-nitro-1,1'-biphenyl-4-yl)-2-oxoethyl]pentanoate

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a 150 mL 3-neck flask fitted with a reflux condenser was added ethyl 2-[2-(4-bromophenyl)-2-oxoethyl]pentanoate (1.33 g, 4.10 mmol) and 4-nitro phenyl boronic acid (0.81 g, 4.9 mmol), dissolved in toluene (37 mL) and dioxane (10 mL), followed by addition of saturated aqueous sodium carbonate (11 mL). A thin-gauge needle was inserted into the bi-phasic mixture and the mixture was degassed with argon over 30 minutes, at which point 1,2-bis[(diphenylphosphino) ferrocene] dichloropalladium(II) (0.17 g, 0.20 mmol) was added, followed by 15 minutes of degassing. The mixture was heated to 85° C. for 16 h. The very darkly colored reaction mixture was allowed to cool, and diluted with ethyl acetate (100 mL) and saturated aqueous sodium chloride solution (100 mL). The layers were separated, the aqueous layer extracted twice with ethyl acetate (50 mL), and the combined organic layers were washed with saturated aqueous sodium chloride solution (75 mL), dried over anhydrous magnesium sulfate, and filtered in vacuo through 2 cm Celite®/2 cm silica. The filtrate was concentrated under reduced pressure, leaving a dark red-brown oil, that was purified by flash chromatography (10:1 hexane:ethyl acetate, then 7:1 hexane:ethyl acetate, then 4:1 hexane:ethyl acetate) to afford ethyl 2-[2-(4′-nitro-1,1′-biphenyl-4-yl)-2-oxoethyl]pentanoate (0.71 g, 48%). LC-MS ret. time 3.88 min, m/z 369.8 (MH+); 1H NMR (300 MHz, CDCl3) δ 0.95 (t, 3H), 1.30 (t, 3H), 1.35–1.50 (m, 2H), 1.60–1.83 (m, 2H), 3.0–3.18 (m, 2H), 3.5 (dd, 1H), 4.20 (q, 2H), 7.65–7.88 (overlapping d, 4H), 8.10 (d, 2H), 8.35 (d, 2H).

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