Phosphorus oxybromide → HCID 11368839, compound

Participants

Reaction Conditions

Reaction Steps

To a 1-Liter 3-neck flask was charged 50 g (0.26 mol) of 2-(4-fluorophenyl)-1,3-cyclopentanedione as a solid to 260 mL of dry MeCN (KF<100 ug/mL). To the resulting suspension was added 18.5 g (0.13 mol) of Na2HPO4 and the sides of the reaction flask were washed with an additional 100 ml of dry MeCN. In a separate flask containing 150 mL of MeCN was added 56 g (0.195 mol) of POBr3. The resulting POBr3 solution was then added drop-wise to the slurry, and the mixture was heated to 65° C. for 1.5 h and cooled to rt. The reaction mixture was quenched with 1N KOH to a final pH of <8.0 and aged for 30 min. During the quench the precipitation of insolubles occurs at pH<4 which turns to an oily mass around pH 7–7.5. The bottom oily layer and aqueous layer were separated. The top MeCN layer containing the product was filtered over a small plug of solka floc, which was then rinsed with one bed volume of MeCN. The combined MeCN layers were then concentrated to a final volume of 500 mL. To the concentrated solution was added 600 mL of water at rt and the mixture seeded with 500 mg of 3-bromo-2-(4-fluorophenyl)-2-cyclopenten-1-one. After aging for 30 min, the remaining 700 mL of water were added drop-wise. After 45 min, the slurry was filtered, washed with 100 mL of water and dried under vacuum at 25° C. giving 3-bromo-2-(4-fluorophenyl)-2-cyclopenten-1-one as a light brown solid.

Provenance & Evidence