Tetrahydrothiophene → 2-Bromo-1-(phenanthren-2-yl)ethan-1-one

Participants

Reaction Steps

Preparation of a sulfonium salt according to Formula 3 wherein X- is CF3SO3- and R1, R2, and S combined are tetrahydrothiophene is as follows. To a stirred solution of 5 grams (22.6 mM) of 2-acetylphenanthrene in a mixture of 30 ml of methylene chloride and 30 ml of diethyl ether cooled in an ice/acetone bath was added 3.5 grains (22 mM) of bromine dropwise over 15 minutes. The red bromine color was immediately discharged upon addition to the stirred solution. The cooling bath was removed and the stirred mixture warmed to room temperature over 30 minutes, then the mixture was stirred at room temperature for 2 hours. The reaction mixture was stripped of solvent on a rotary evaporator, then was suspended in 50 ml diethyl ether and evaporated to dryness. This process was repeated twice more to remove the byproduct hydrogen bromide from the solid product. The residual solid was triturated with 15 ml cold diethyl ether, filtered, and dried in a vacuum oven to yield 4.35 grams of 2-(bromoacetyl)-phenanthrene.

Provenance & Evidence