Nitric Acid → Carbonic acid 2,3-difluoro-4-methyl-5-nitro-phenyl ester methyl ester

To a suspension of carbonic acid 2,3-difluoro-4-methyl-phenyl ester methyl ester (3.85 g, 19.04 mmol) in sulfuric acid (2.23 ml) at 0° C. was added nitric acid (2.23 ml). The mixture was stirred at 0° C. for one hour. Ice-water was added and the mixture was extracted with dichloromethane. The combined extracts were washed with water and brine, dried over MgSO4, filtered and concentrated to dryness under reduced pressure. Purification of the crude product by flash chromatography (hexanes:EtOAc 95:5) gave 2.3 g (49%) of carbonic acid 2,3-difluoro-4-methyl-5-nitro-phenyl ester methyl ester a clear oil.