N,N-Dimethylaniline → 4-Bromobenzo[g]quinoline

Participants

Reaction Conditions

Reaction Steps

Crude benzo[g]quinolin-4-ol (6) (5.07 mmol) was dissolved in 50 mL of acetonitrile (0.1 M) and cooled to 0° C. under a nitrogen atmosphere. N,N-dimethylaniline (3.2 mL, 5 equivalents) was added followed by 3.3 g of phosphorus pentabromide (1.5 equivalents). After removal of the bath, the mixture was heated to reflux and followed by TLC until complete. Upon cooling to rt, the mixture was slowly poured onto ice water and extracted with methylene chloride three times. The organic layers were combined, washed with brine, dried with magnesium sulfate, and concentrated in vacuo. Flash chromatography (gradient: 9:1 to 8:2 to 7:3 hexanes:EtOAc) afforded 736 mg of clean 4-bromobenzo[g]quinoline (7a) in 55% yield for the 2 steps.

Provenance & Evidence