Pyridine → 5-bromo-1H-indene

Participants

Reaction Steps

A 1 L three-neck round bottom flask equipped with a condenser, magnetic stir bar, nitrogen inlet, and a thermometer was charged with 5-bromo-1-indanol (56.5 g, 0.265 mol), toluene (300 mL), pyridine (250 mL, 3.1 mol), and p-toluenesulfonyl chloride (55.3 g, 0.29 mol). The mixture was stirred and heated to reflux while dehydration progress was followed by GC. After 7 hours at reflux the dark colored reaction mixture was cooled, quenched by pouring over ice-water (700 mL) containing HCl (12M, 200 mL) and extracted several times with diethyl ether (3×250 mL). The combined diethyl ether extracts were washed repeatedly with water, 5% sodium bicarbonate (aqueous), and water then dried over anhydrous magnesium sulfate. Evaporation of diethyl ether followed by vacuum distillation (80° C./0.5 mm Hg) gave 5-bromoindene (24.0 g, 99+% purity by GC) as a colorless oil. 1HNMR (CD2Cl2, 500 MHz) δ7.59 (br s, 1H); 7.38 (dd, JAB=1.5, 8 Hz, 1H), 7.26 (d, JAB=8 Hz, 1H); 6.84 (m, 1H); 6.56 (m, 1H); 3.39 (s, 2H).

Provenance & Evidence