Water → 2-Biphenyl-3-yl-4-methylpent-4-enoic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

A solution of biphenyl-3-yl acetic acid (7.0 g, 33 mmol) in anhydrous tetrahydrofuran (84 mL) was added dropwise to a solution of lithium diisopropyl amide (36.4 mL, 2M solution in hexanes) in anhydrous tetrahydrofuran (84 mL) at −78° C. The mixture was allowed to warm to 0° C. and stirred for 40 min. The mixture was then cooled to −78° C. and 3-bromo-2-methylpropene (4.97 mL) rapidly added. The mixture was stirred for 1 h at −78° C. then water (28 mL) added and the organics removed under reduced pressure. The mixture was then acidified with hydrochloric acid (6M, 14 ml), extracted with ethyl acetate (3×100 ml), dried (MgSO4) and evaporated under reduced pressure to afford a residue. Flash chromatography of the residue over silica (400 g) using methanol:dichloromethane (3:97) as the eluent afforded impure 2-biphenyl-3-yl-4-methylpent-4-enoic acid (8.3 g). Flash chromatography over silica (400 g) using methanol:dichloromethane (1.5:98.5) afforded pure 2-biphenyl-3-yl-4-methylpent-4-enoic acid, yield 5.27 g, (60%), TLC (single UV spot, Rf=0.28, 5% methanol in dichloromethane), analytical HPLC Rt=19.99 min, HPLC-MS (single main UV peak with Rt=9.57 min, 267.1 [M+H]+).

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