Water → Benzofuran, 5-bromo-

Temperature

150 °C

A solution of 4-bromophenol (17.3 g, 100 mmol) in dimethylformamide (40 ml) was treated with bromoacetaldehyde dimethyl acetal (16.9 g, 100 mmol) and potassium carbonate (13.8 g, 100 mmol) and heated at 150° C. for 16 h. The mixture was cooled, poured into water (500 ml) and extracted with diethyl ether (3×100 ml). The combined organic extracts were dried (MgSO4), concentrated, and filtered through a plug of silica gel eluting with 10% diethyl ether in hexane. The resulting oil (15 g) was added to a solution of polyphosphoric acid (~12 g) in toluene (100 mL) and heated at 80° C. for 16 h. The mixture was cooled and the toluene layer was decanted off and washed with saturated aqueous sodium hydrogen carbonate, dried (MgSO4), concentrated and the residue distilled to give 5-bromobenzofuran (6 g) as a colourless oil, bp. 98° C./1 mmHg; δH (DMSO-d6) 6.96 (1H, m, ArH), 7.45 (1H, m, ArH), 7.59 (1H, m, ArH), 7.91 (1H, m, ArH), and 8.05 (1H, m, ArH).

1. temperatureThe mixture was cooled
2. extractionextracted with diethyl ether (3×100 ml)
3. dry with materialThe combined organic extracts were dried (MgSO4)
4. concentrationconcentrated
5. filtrationfiltered through a plug of silica gel eluting with 10% diethyl ether in hexane
6. additionThe resulting oil (15 g) was added to a solution of polyphosphoric acid (~12 g) in toluene (100 mL)
7. temperatureheated at 80° C. for 16 h
8. temperatureThe mixture was cooled
9. customthe toluene layer was decanted off
10. washwashed with saturated aqueous sodium hydrogen carbonate
11. dry with materialdried (MgSO4)
12. concentrationconcentrated
13. distillationthe residue distilled

ORD record

ord-c4ecce3b03ab46b887013a11c6cfea41

Source dataset

uspto-grants-1997_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05700809