Sodium Carbonate → 3-(4,4-dimethyl-8-methoxy-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-5-fluorobenzonitrile

Participants

Reaction Conditions

Reaction Steps

A mixture of 6-bromo-8-methoxy-4,4-dimethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one (1.6 g, 5.6 mmol), bis(pinacolato)diboron (1.6 g, 6.3 mmol), potassium acetate (1.5 g, 15.3 mmol), and [1,1′-bis(diphenylphosphino)ferrocene]palladium (II) chloride (1:1 complex with methylene chloride, 0.5 g, 0.6 mmol) in DMF (30 mL) was subject to a positive flow of nitrogen to remove oxygen and then heated at 85° C. under a blanket of nitrogen for 18 hours. The reaction mixture was allowed to cool to ambient temperature, treated with 3-bromo-5-fluoro-benzonitrile (1.2 g, 6 mmol), [1,1′-bis(diphenylphosphino)ferrocene]palladium (II) chloride (1:1 complex with methylene chloride, 0.5 g, 0.6 mmol), and sodium carbonate (2 g, 19 mmol) in water (10 mL). The resulted solution was heated at 85° C. for 3 hours under a blanket of nitrogen, cooled to rt, and treated with brine (50 mL). Ethyl acetate (100 mL) was added, organic layer was separated, dried (MgSO4), and evaporated. The residue was purified by a flash silica gel column chromatography (THF:hexane/2:3) to yield 3-(4,4-dimethyl-8-methoxy-2-oxo-1,4-dihydro-2H-3,1-benzoxazin-6-yl)-5-fluorobenzonitrile as a white solid (0.6 g, 33%): mp 252-253° C.; 1H-NMR (DMSO-d6) δ9.76 (s, 1H), 8.21 (s, 1H), 8.07 (d, 1H, J=10.6 Hz), 7.82 (m,1H), 7.39 (s 1H), 7.36 (s, 1H), 3.93 (s, 3H), 1.66 (s, 6H). MS (ESI) m/z 325 [M−H]−.

Provenance & Evidence