Propylphosphonic anhydride → Ethyl {7-chloro-4-[(3-oxo-3,4-dihydro-2H-1,4-benzoxazin-6-yl)carbonyl]-3,4-dihydro-2H-1,4-benzoxazin-3-yl}acetate

Participants

Reaction Conditions

Reaction Steps

Ethyl (7-chloro-3,4-dihydro-2H-1,4-benzoxazin-3-yl)acetate (Intermediate 20, 0.67 g, 2.62 mmol), 3-oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylic acid (0.607 g, 3.14 mmol), and TEA (1.090 mL, 7.86 mmol) were dissolved in EtOAc (15 mL). Then T3P (50 wt. % in EtOAc, 3.12 mL, 5.24 mmol) was added and the mixture was heated in a microwave reactor for 2 h at 160° C. EtOAc (100 mL) was added and the mixture was washed with sat. aq. NaHCO3 (100 mL), 1 M HCl (100 mL) and brine (100 mL). The mixture was dried by passage through a phase separator. Concentration under reduced pressure gave 1.14 g of an oil that was purified by flash chromatography on silica gel using a gradient from 12% to 100% of EtOAc in heptane as eluent. Concentration to dryness gave the title compound (0.530 g, 46.9%).

Provenance & Evidence