Dihydrobenzofuran → 5-Bromo-2,3-dihydro-1-benzofuran

To a chilled (10° C.) solution of 10 g (83 mmol) of 2,3-dihydrobenzofuran in 50 mL of acetic acid, 4 mL (78 mmol) of bromine in 6 mL of acetic acid was added dropwise over a 10 minute period. After 1 hour, the mixture was made basic by cautiously pouring the reaction mixture into saturated/solid aqueous sodium bicarbonate solution and stirring overnight. The mixture was then extracted with three 100 mL portions of EtOAc. The combined organic layers were washed with two 50 mL portions of saturated aqueous sodium bicarbonate, three 50 mL portions of brine, dried over magnesium sulfate, filtered, and concentrated to afford a yellow oil. The oil was diluted with hexanes and passed through a pad of silica gel in a 600 mL funnel eluting with hexanes to afford a white solid which was diluted with cold (dry ice-acetone) hexanes and collected by filtration to afford 4.7 g (28%) of 5-bromo-2,3-dihydrobenzofuran as a white solid, mp 45° C.-48° C. The filtrate was concentrated to afford 5.1 g of 5-bromo-2,3-dihydrobenzofuran which was 70% pure.

1. additionwas added dropwise over a 10 minute period
2. extractionThe mixture was then extracted with three 100 mL portions of EtOAc
3. washThe combined organic layers were washed with two 50 mL portions of saturated aqueous sodium bicarbonate, three 50 mL portions of brine
4. dry with materialdried over magnesium sulfate
5. filtrationfiltered
6. concentrationconcentrated
7. customto afford a yellow oil
8. custompassed through a pad of silica gel in a 600 mL funnel
9. washeluting with hexanes
10. customto afford a white solid which
11. filtrationcollected by filtration

ORD record

ord-399d4bbf5ba74321ba3b88c2067dd4cc

Source dataset

uspto-grants-2005_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06903215B2