2-Bromo-m-xylene → 1,3,2-Dioxaborolane, 2-(2,6-dimethylphenyl)-4,4,5,5-tetramethyl-

Reaktionsgleichung

[CH3:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([CH3:8])[C:3]=1Br.[Li]CCCC.C(O[B:19]1[O:23][C:22]([CH3:25])([CH3:24])[C:21]([CH3:27])([CH3:26])[O:20]1)(C)C>>[CH3:1][C:2]1[CH:7]=[CH:6][CH:5]=[C:4]([CH3:8])[C:3]=1[B:19]1[O:23][C:22]([CH3:25])([CH3:24])[C:21]([CH3:27])([CH3:26])[O:20]1

Komponenten

Edukt 3

HCID 684712-Bromo-m-xylene

HCID 50177412-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane

HCID 178418339Butyllithium

Produkt 1

HCID 104897161,3,2-Dioxaborolane, 2-(2,6-dimethylphenyl)-4,4,5,5-tetramethyl-

Versuchsvorschrift

To a solution of 35.0 g (0.19 mol) of 2,6-dimethylbromobenzene cooled to −78° C., 76 ml (0.19 mol) of 2.5 M nBuLi in hexanes was added for 40 min. The resulting mixture was stirred at this temperature for 1 h, then 35.2 g (0.19 mol) of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was added. The resulting mixture was stirred overnight at room temperature and then evaporated to dryness. The residue was poured into 500 ml of water, crude product was extracted with 3×200 ml of ethyl acetate. The combined organic extract was dried over Na2SO4 and then evaporated to dryness. Yield 19.5 g (53%) of yellow crystalline solid. Anal. calc. for C14H21BO2: C, 72.44; H, 9.12. Found: C, 72.78; H, 9.45. 1H NMR (CDCl3): δ 7.12 (t, J=7.7 Hz, 1H, 4-H), 6.94 (d, J=7.7 Hz, 2H, 3, 5-H), 2.40 (s, 6H, 2, 6-Me), 1.38 (s, 12H, Bpin).