Propylphosphonic anhydride → Ethyl {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

T3P (50% solution in EtOAc, 132.4 g, 0.208 mol) was added to 3-oxo-3,4-dihydro-2H-1,4-benzoxazine-6-carboxylic acid (22.1 g, 0.114 mol), ethyl-2-(3,4-dihydro-2H-1,4-benzoxazin-3-yl)acetate (23.0 g, 0.104 mol) and TEA (57.9 mL, 0.416 mol) in EtOAc (139 mL) at rt. The resulting mixture was stirred at 75° C. for 16 h. The resulting solution was diluted with 800 mL of EtOAc and washed with aq. sat. NaHCO3 solution (300 mL), 0.5 M HCl solution (300 mL) and brine (300 mL). The organic phase was dried over anhydrous Na2SO4, filtered and evaporated to afford crude product. The crude product was purified by re-crystallization from MeOH to afford the title compound (14.5 g, 35%) as a white solid.

Provenance & Evidence