A suspension of 6-bromo-2-(4-nitrophenyl)-1,3-benzodioxan (2.05 g) in toluene (150 ml) was hydrogenated at ≤60 psi hydrogen pressure in the presence of 5% platinum/charcoal (0.5 g) and anhydrous potassium carbonate (0.5 g) at ambient temperature. The reaction mixture was filtered and evaporated under reduced pressure, azeotropically removing the water formed in the reaction. The resulting crude aniline derivative was redissolved in dry toluene (25 ml) and treated with 2,6-difluorobenzoyl isocyanate (1.2 g), warming briefly to approx. 60° C. then allowing the stirred reaction mixture to cool overnight. Cooling to 0°-5° C. afforded a precipitate of impure product which was purified by crystallisation from ethanol (0.52 g, 17%), mp 194°-195° C.
