2-(7-Fluoro-1,2,3,4-tetrahydrocyclopenta[b]indol-3-yl)acetic acid → 2-(5-Bromo-7-fluoro-1,2,3,4-tetrahydrocyclopenta[b]indol-3-yl)acetic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 2.20 g of the acid from Step 2 (>90% purity) in 30 mL of pyridine, 6.85 g of pyridinium tribromide (90% purity) was added at −40° C. The suspension was stirred for 10 min at 0° C. and warmed to room temperature for 30 min. Then, the solvent was removed without heating under high vacuum. The crude material was dissolved in 40 mL of AcOH and 2.88 g of Zn dust was added portion wise to the cold solution at 0° C. The suspension was stirred for 15 min at 15° C. and warmed to room temperature for an additional 15 min. At this time, the reaction mixture was quenched by the addition of 1N HCl and this mixture was poured into a separatory funnel containing brine/EtOAc. The layers were separated and the organic layer was washed with water, brine, dried over anhydrous Na2SO4 and concentrated. This material was used without further purification in the next step.

Provenance & Evidence