Triphosgene → (5R)-5-ethyl-5-methyl-3-[6-[(2,4,4-trimethyl-3,1-benzoxazin-5-yl)oxy]-3-pyridyl]imidazolidine-2,4-dione

Participants

Reaction Conditions

Reaction Steps

To a solution of (2R)-2-amino-2-methyl-N-[6-[(2,4,4-trimethyl-3,1-benzoxazin-5-yl)oxy]-3-pyridyl]butanamide (Intermediate 205, 143 mg, 0.37 mmol) and TEA (0.21 mL) in ethyl acetate (2.5 mL) at 0° C., triphosgene (44 mg, 0.15 mmol) dissolved in ethyl acetate (2.5 mL) was added drop wise in 10 min. The reaction mixture was stirred at 0° C. for 40 min. The reaction mixture was diluted with water (5 mL) and ethyl acetate (10 mL). Phases were separated and the aqueous was back-extracted with ethyl acetate (2×10 mL). The combined organic layers were washed with brine (15 mL), dried over Na2SO4, filtered and concentrated and the residue was purified by flash chromatography on silica gel using ethyl acetate as eluent affording the title compound (115 mg) as white solid.

Provenance & Evidence