alpha-Methylbutyrolactone → 4-Hydroxy-1-(2-chloro-4-methoxyphenyl)-2-methylbutan-1-one

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a 1.0 L, 3-neck round bottom flask, equipped with a mechanical stirrer and an internal thermometer, was added a solution of 4-bromo-3-chloroanisole (12.0 g, 54.0 mmol) in 350 mL of THF under nitrogen. The solution was cooled to −85° C. with a MeOH/liquid nitrogen bath. To this solution was added t-BuLi (72.0 mL, 1.6 M in pentane, 122 mmol) slowly followed by the addition of a solution of α-methyl-γ-butyrolactone (9.25 g, 92.0 mmol) in THF (30.0 mL). The internal temperature was controlled <−80° C. After 1 h stirring at <−80° C., the reaction mixture was quenched with saturated NH4Cl solution and warmed to room temperature. Water and EtOAc were added and separated. The aqueous layer was extracted with EtOAc (2×). The combined organic solutions was dried (MgSO4) and filtered. The filtrate was concentrated in vacuo to dryness. The residue was subjected to column chromatography (E:H, 1:3) to give 10.4 g (79%) of brown oil as the title compound: 1H NMR (400 MHz, CDCl3) δ 7.53 (d, J=8.6 Hz, 1H), 6.97 (d, J=2.4 Hz, 1H), 6.85 (dd, J=8.6, 2.4 Hz, 1H), 3.88 (s, 3H), 3.77–3.69 (m, 2H), 3.64–3.56 (m, 1H), 2.16–2.07 (m, 1H), 1.76–1.67 (m, 1H), 1.23 (d, J=7.0 Hz, 3H); MS (EI m/z 241.16 (M+−H).

Herkunft & Nachweise