Trifluoroacetic anhydride → 3-bromo-5H,6H,7H-cyclopenta(b)pyridin-7-ol

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Reaction Steps

3-Bromo-6,7-dihydro-5H-[1]pyrindine 1-oxide (6.97 g, 32.6 mmol) was dissolved in CH2Cl2 (150 ml); then, trifluoroacetic anhydride (20.5 g, 13.6 ml, 97.7 mmol) was added drop by drop below 25° C. with intense stirring and stirring was continued for 6 hours at RT. The mixture was then quenched with aqueous 1M NaOH solution. The aqueous mixture was stirred for two hours and extracted three times with CH2Cl2/2-propanol 4:1. The organic layers were dried over MgSO4, filtered and concentrated in vacuo to give a crude product (6.279 g) which was purified by flash chromatography (silica gel, 50 g, 20% to 100% EtOAc in heptane) to yield the title compound (5.38 g, 77%) as light brown solid. MS: 214.0 (MH+, 1Br).

Provenance & Evidence