Br[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][C:3]=1[N+:8]([O-:10])=[O:9].C(B(CC)[C:14]1[CH:15]=[N:16][CH:17]=[CH:18][CH:19]=1)C.C(=O)([O-])[O-].[Na+].[Na+].O>O1CCCC1.[Pd](Cl)Cl.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(Cl)Cl.CO>[N+:8]([C:3]1[CH:4]=[CH:5][CH:6]=[CH:7][C:2]=1[C:14]1[CH:15]=[N:16][CH:17]=[CH:18][CH:19]=1)([O-:10])=[O:9]
To a mixture consisting of 1-bromo-2-nitrobenzene (2.12 g, 8.7 mmol), diethyl (3-pyridyl) borane (1.47 g, 10.0 mmol), and bis (triphenylphosphine) palladium (II) chloride (913 mg, 1.3 mmol) in tetrahydrofuran (40 ml), sodium carbonate (4.24 g, 40.0 mmol) was added, and the resulting reaction mixture was heated at reflux for 4 hours. Water (40 ml) was added to the cooled reaction mixture which was then extracted with three 25 ml portions of ethyl acetate. The combined organic extracts were dried (anhydrous sodium sulfate) and concentrated in vacuo to afford a tacky residue. Flash chromatography of the entire sample (silica gel, 47-61 micron mesh; elution initially with methylene chloride and finally with methylene chloride/methanol=98:2 in volume) afforded the title compound as a viscous amber oil (713 mg, 41% yield). Subsequent eluent contained less pure product which was further purified by a similar flash chromatography, eluting with methylene chloride/methanol=99:1 in volume, thus affording an additional 488 mg (28% yield) of the purified title compound, again as a viscous amber oil.
Wird geladen…
