Pyridine → 4,4'-(Bromomethylene)bis(methoxybenzene)

Participants

Reaction Conditions

Reaction Steps

Bis(4-methoxyphenyl)methanol (2.0 g, 8.2 mmol) was dissolved in toluene (60 mL) and pyridine (661 μL, 8.2 mmol)) was added. The solution was cooled to 0° C. PBr3 (768 μL, 8.2 mmol) was added dropwise over 15 min. The reaction mixture was warmed to room temperature and stirred for 1 h. The mixture was washed with K2CO3 solution and extracted with EtOAc (3×30 mL). The EtOAc layer was washed with brine and dried (MgSO4). The solvent was evaporated off in-vacuo to give the crude product 4,4′-(bromomethylene)bis(methoxybenzene) (780 mg, 31%), as a colourless oil. This was used in the next reaction step without further purification. Sodium ethoxide (133 mg, 1.96 mmol) was added to DMF (5 mL) at 0° C., and the suspension was stirred for 10 min. 7-hydroxy-4-methylcoumarin (345 mg, 1.96 mmol) was slowly added and resulting mixture was stirred at this temp for 0.5 h. To this mixture 4,4′-(bromomethylene)bis(methoxybenzene (500 mg, 1.63 mmol) was added portionwise. Resulting reaction mixture was stirred at room temperature for 16 h. DMF was evaporated off in-vacuo and the residue was taken up in EtOAc, and washed with brine, water and 1M NaOH (2×30 mL). The organic layer was dried (MgSO4) and product was purified by flash chromatography, eluting with hexane:EtOAc (2:1) to give 49 (100 mg, 15%) as a white solid. Mpt=142-145° C. m/z=403 (M+H). H1 NMR (500 MHz, acetone-d6): δ=7.60 (1H, d, ArH), 7.45 (4H, d, ArH), 7.04 (1H, d, ArH), 6.94 (5H, d, ArH), 6.56 (1H, s ArH), 6.10 (1H, s, qCH), 3.78 (6H, s, 2×CH3O), 2.39 (3H, s, CH3). 13C NMR (500 MHz, acetone-d6, DEPT 135): δ=206.3 (qC), 134.1 (2×qC), 129.3 (2×CH), 129.2 (2×CH), 129.0, (2×CH), 126.9 (Ar CH), 114.4 (Ar CH), 114.7 (Ar CH), 115.1 (Ar CH), 112.5 (Ar CH), 104.0 (Ar CH), 81.7 (CH), 55.6 (2×CH3), 18.2 (CH3).

Provenance & Evidence