Methanol → 4-Bromo-2,6-dimethoxyphenol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a 2 liter flask equipped with a magnetic stirrer, thermometer, and nitrogen inlet, was added 77 g (0.5 mol) of pyrogallol 1,3-dimethyl ether. 5.8 ml of MeOH, and 750 ml of CH2Cl2. To this solution was added 126 mg (5 mmol) of NaH (95%). The solution was stirred while cooling to −45° C. with a dry-ice acetone bath. 94 g (0.53 mol) of powdered N-bromosuccinimide was added rapidly. The reaction mixture was then stirred for 1 hour at −35° C., heated to room temperature over next 30 min, and finally refluxed for 30 min. The CH2Cl2 was removed under reduced pressure and the residue solidified. The tan solid was broken up and stirred well with 1 liter of ether. This was filtered and the residue was washed well with ether. The ether was evaporated under reduced pressure to yield a tan solid. The solid was placed in a 5 liter flask with 3 liters of ligroin (bp: 90-110° C.) and heated with stirring to 80° C. The hot solution was decanted from the brown oil and the hot yellow solution was allowed to cool at room temperature for 3 hr. The white needles was filtered off and dried to yield 74 g (63%) of 17.

Herkunft & Nachweise