Trifluoroacetic anhydride → 8-(cyclopentyloxy)-4-(3,5-dichloropyridin-4-ylamino)-3-hydroxy-7-methoxy-2H-chromen-2-one

Participants

Reaction Steps

Trifluoroacetic anhydride (0.04 mL, 0.29 mmol) was added to a solution of 8-(cyclopentyloxy)-4-(3,5-dichloropyridin-4-ylamino)-7-methoxy-2H-chromen-2-one (42 mg, 0.1 mmol, Example 3), urea•H2O2 (28.5 mg, 0.3 mmol), and dichloromethane (2 mL) at rt under N2. After 1.5 h, sat'd Na2S2O3 (8 mL) was added, and the mixture was stirred vigorously for 15 min. The reaction was then diluted with 0.5N HCl (40 mL), and extracted with dichloromethane (40 mL×2). The combined extracts were dried, filtered, concentrated, and purified by silica gel chromatography (4:1→1:1; hexanes:ethyl acetate) to give 8-(cyclopentyloxy)-4-(3,5-dichloropyridin-4-ylamino)-3-hydroxy-7-methoxy-2H-chromen-2-one: 1H NMR (400 MHz, DMSO-d6): δ 9.30 (s, 1H), 8.42 (s, 2H), 8.40 (s, 1H), 7.59 (d, 1H), 7.12 (d, 1H), 4.84 (m, 1H), 3.86 (s, 3H), 1.90-1.50 (m, 8H); MS (ESI): 436.9.

Provenance & Evidence