Ammonia → 2-({3-Nitro-4-[4-(2-oxo-2H-3,1-benzoxazin-1(4H)-yl)piperidin-1-yl]phenyl}carbonyl)benzamide

A solution of the product from example 1 (0.9 g) and carbonyldiimidazole (1.1 equiv.) in dichloromethane (4 ml) was stirred at room temperature for 1 h, poured onto aqueous ammonia and stirred for a further 1 h. The mixture was extracted with ethyl acetate, the organics washed with water, dried and evaporated under reduced pressure. Purification was by chromatography eluting with 2.5% methanol/dichloromethane. Yield 0.01 g as a solid.