Methyl 4-bromo-2-methylbenzoate → Methyl 4-cyclobutyl-2-methylbenzoate
Reaktionsgleichung
[Br-].[CH:2]1([Zn+])[CH2:5][CH2:4][CH2:3]1.Br[C:8]1[CH:17]=[CH:16][C:11]([C:12]([O:14][CH3:15])=[O:13])=[C:10]([CH3:18])[CH:9]=1>>[CH:2]1([C:8]2[CH:17]=[CH:16][C:11]([C:12]([O:14][CH3:15])=[O:13])=[C:10]([CH3:18])[CH:9]=2)[CH2:5][CH2:4][CH2:3]1Komponenten
3
Reaktionsbedingungen
- Temperatur
- 65 °C
Versuchsvorschrift
Cyclobutylzinc(II) bromide (50 ml, 0.5 M in THF, 25.0 mmol) was added to a mixture of methyl 4-bromo-2-methylbenzoate (compound 152.1, 5.2 g, 22.7 mmol) and PdCl2(dppf)CH2Cl2 (1.85 g, 2.27 mmol). The mixture was degassed and the flask was filled with argon through a balloon. The mixture was heated at 65° C. under argon for 24 hours. The mixture was cooled to 0° C. and quenched with water (10 ml). The mixture was diluted with EtOAc (200 ml), washed with water then with brine. The EtOAc layer was dried (Na2SO4), concentrated under reduced pressure, and purified using column (silica gel) chromatography (hexanes:EtOAc 30:1 to 20:1). Yield: 4.1 g, clear oil, 89.1%. 1H NMR (400 MHz, Chloroform-d) δ 7.86 (d, 1H), 7.12-7.02 (m, 2H), 3.88 (s, 3H), 3.59-3.48 (m, 1H), 2.59 (s, 3H), 2.35 (m, 2H), 2.22-1.96 (m, 3H), 1.86-1.84 (m, 1H).