Triisopropyl borate → B-[2,5-Dimethoxy-4-(phenylmethoxy)phenyl]boronic acid
Reaktionsgleichung
[CH2:1]([O:8][C:9]1[CH:14]=[C:13]([O:15][CH3:16])[C:12](Br)=[CH:11][C:10]=1[O:18][CH3:19])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[B:20](OC(C)C)([O:25]C(C)C)[O:21]C(C)C>>[CH2:1]([O:8][C:9]1[C:10]([O:18][CH3:19])=[CH:11][C:12]([B:20]([OH:25])[OH:21])=[C:13]([O:15][CH3:16])[CH:14]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1Komponenten
3
Reaktionsbedingungen
- Temperatur
- -78 °C
Versuchsvorschrift
1-Benzyloxy-4-bromo-2,5-dimethoxybenzene 4 (7.48 g,23.0 mmol) was placed in a dry flask and flushed with Ar. Dry THF (75 mL) was added and the solution was cooled to −78° C. in a dry ice/acetone bath. nBuLi (11 mL, 2.5M in hexanes) was added and the mixture was stirred for 20 min at −78° C. Triisopropyl borate (10.7 mL, 0.463 mol) was added and the reaction stirred for 2 h at −78° C. then allowed to come to room temperature at which time a white precipitate began to form. After stirring for an additional 20 h the reaction was quenched with saturated NH4Cl (25 mL). After separating the organic layer the aqueous layer was extracted with ethyl acetate (2×50 mL). The organic layers were combined, dried and concentrated. The residue was triturated with hexanes and filtered to give 4.1 g (62%) of 5b as a light off-white creamy solid. 1H-NMR (400 MHz, DMSO-d6) dH 3.70 (3H, s, OCH3), 3.79 (3H, s, OCH3), 5.16 (2H, s, CH2Ph), 6.77 (1H, s, ArH), 7.18 (1H, s, ArH), 7.33-7.52 (5H, m, CH2Ph)