Pentane → 2-Methyl-4-methylthiophenylboronic acid

Temperature

-78 °C

1.7M tert-Butyllithium in pentane (6.70 mL, 11.39 mmol) was added dropwise to a solution of 1-bromo-2-methyl-4-(methylthio)benzene (1.2 g, 5.53 mmol) in diethyl ether (120 mL) at −78° C. over 15 min. The mixture was stirred at −78° C. for 2 min, then charged with trimethyl borate (0.661 mL, 5.91 mmol) dropwise over 2 min at −78° C., stirred at −78° C. for 15 min, then brought to ambient temperature. The mixture was quenched with saturated aqueous NH4Cl (14 mL), stirred at ambient temperature for 15 min, charged with 1M HCl (12 mL), stirred at ambient temperature for 2 min, and the organics were separated. The organics were dried over MgSO4, filtered, and the filtrate was concentrated. The crude product was purified by chromatography on a silica gel column using 20 to 100% EtOAc/hexane to give 503 mg (50%) of [2-methyl-4-(methylthio)phenyl]boronic acid as a white solid. 1H NMR (400 MHz, DMSO-d6): δ 7.79 (d, 1H, J=7.8 Hz), 7.09-7.00 (m, 2H), 2.61 (s, 3H), 2.46 (s, 3H); LRMS (ESI), m/z 183 (M+H).

1. stirringstirred at −78° C. for 15 min
2. custombrought to ambient temperature
3. customThe mixture was quenched with saturated aqueous NH4Cl (14 mL)
4. stirringstirred at ambient temperature for 15 min
5. additioncharged with 1M HCl (12 mL)
6. stirringstirred at ambient temperature for 2 min
7. customthe organics were separated
8. dry with materialThe organics were dried over MgSO4
9. filtrationfiltered
10. concentrationthe filtrate was concentrated
11. customThe crude product was purified by chromatography on a silica gel column

ORD record

ord-0763221d05e04016892eae0868bd4ba3

Source dataset

uspto-grants-2012_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08101634B2