Azidotrimethylsilane → ethyl 2-(5-azido-7-bromo-3-chloro-5H-chromeno[2,3-c]pyridin-5-yl)acetate

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Reaction Steps

To a solution of ethyl 2-(7-bromo-3-chloro-5-hydroxy-5H-chromeno[2,3-c]pyridin-5-yl)acetate (20 g, 50.2 mmol) in toluene (300 ml) was added azidotrimethylsilane (19.93 ml, 151 mmol), followed by (diethyloxonio)trifluoroborate (12.72 ml, 100 mmol). The mixture was stirred overnight at RT. The reaction mixture was quenched with MeOH (200 mL) and diluted with EtOAc. The organic phase was separated, washed with saturated aqueous sodium bicarbonate solution and brine. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure to afford ethyl 2-(5-azido-7-bromo-3-chloro-5H-chromeno[2,3-c]pyridin-5-yl)acetate (21 g, 49.6 mmol, 99% yield).

Provenance & Evidence