General procedure for the synthesis of methyl 2-methoxy-6-nitrobenzoate from 2-methyl-3-nitroanisole and tert-butanol: Potassium permanganate (KMnO4, 5.7 g, 36 mmol) was added to a suspension of 2-methyl-3-nitroanisole (2.0 g, 12 mmol) in tert-butanol (10 mL) and water (20 mL). The reaction mixture was heated to reflux and kept for 4 hours. After completion of the reaction, the cooled mixture was filtered through diatomaceous earth. The filtrate was acidified with 12N aqueous hydrochloric acid and subsequently extracted twice with ethyl acetate (EtOAc). The organic layers were combined, washed sequentially with water and saturated saline, dried over anhydrous magnesium sulfate (MgSO4), filtered and concentrated under reduced pressure. The resulting residue was treated with excess diazomethane/ether (Et2O) solution to afford the target product methyl 2-methoxy-6-nitrobenzoate (548 mg, 22% yield).
