Scheme 4, Step C: Methyl 2,4-dimethyl-3-nitrobenzoate (37 g, 176.9 mmol) was dissolved in methanol (370 mL) and 10% palladium/carbon (50% wet, 5.6 g) was added. Hydrogen was bubbled into the reaction mixture under hydrogen atmosphere and the reaction was continued for 6 days. Upon completion of the reaction, the mixture was filtered through diatomaceous earth and the filtrate was concentrated to dryness under reduced pressure. The resulting residue was purified by fast column chromatography (silica gel, eluent: hexane solution of 20% ethyl acetate) to afford methyl 3-amino-2,4-dimethylbenzoate as a yellow oil (20.5 g, 65% yield). Mass spectrum (m/z): 180.1 (M + 1). 1H NMR (300.16 MHz, DMSO-d6): δ 6.89 (s, 2H), 4.78 (s, 2H), 3.76 (s, 3H), 2.23 (s, 3H), 2.12 (s, 3H).
