Ethylene → 7-Bromo-2-tetralone

Participants

Reaction Steps

A solution of 3-bromophenylacetic acid (10.4 g, 48.4 mmol) in oxalyl chloride (50 mL, 0.57 mol) was stirred at ambient temperature for 5 min then at reflux for 5 h. The oxalyl chloride was removed in vacuo and the residue was dissolved in anhydrous CH2Cl2 (100 mL). This solution was added dropwise to a rapidly stirred, ice-cooled solution of AlCl3 (23.2 g, 174.2 mmol) in CH2Cl2 (500 mL). A stream of ethylene gas was blown into the vortex of the stirred solution during the addition and the reaction temperature was kept at <5° C. The reaction mixture was allowed to warm to ambient temperature and then poured onto ice and stirred vigorously. The organic portion was removed and the aqueous layer extracted with CH2Cl2 (2×200 mL). The combined CH2Cl2 fractions were passed through a 2″ pad of silica and concentrated to give a thick, red oil. The crude product was purified by silica gel chromatography, eluting with a gradient of hexane:EtOAc—100:0 to 75:25, to provide the title compound as a pale yellow solid. MS: m/z=226 (M+1).

Provenance & Evidence