Boron tribromide → 5-Amino-4'-fluoro-7'-(2-fluoropyridin-3-yl)-2,6-dihydrospiro[[1,4]oxazine-3,9'-xanthen]-2'-ol

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Reaction Steps

To a suspension of 4′-fluoro-7′-(2-fluoropyridin-3-yl)-2′-methoxy-2,6-dihydrospiro[[1,4]oxazine-3,9′-xanthen]-5-amine (1.668 g, 4.07 mmol) in DCM (12 ml) was added boron tribromide (0.963 mL, 10.19 mmol). Stirring was continued for 45 hrs at 0° C. at which point the mixture was removed from the bath and stirred for 2 hrs at RT. The reaction mixture was recooled to 0° C. and quenched by careful addition of saturated aqueous NaHCO3 solution (˜10 mL). The mixture became colorless with a white precipitate. The solvent was removed in vacuo, the mixture was diluted with water and filtered. The solid was washed with water and dried on air for 2 hrs, then for 2 hrs in high vacuum at RT to afford 5-amino-4′-fluoro-7′-(2-fluoropyridin-3-yl)-2,6-dihydrospiro[[1,4]oxazine-3,9′-xanthen]-2′-ol (1.53 g, 3.87 mmol, 95% yield).

Provenance & Evidence