The general procedure for synthesizing methyl 2-amino-6-hydroxybenzoate from indirubic anhydride is as follows:Example 386B Synthesis of methyl 2-amino-6-hydroxybenzoate. Example 386A (1.0 g, 5.6 mmol) was mixed with methanol (40 mL) and heated to reflux for 6 hours. Upon completion of the reaction, the mixture was concentrated and purified by silica gel column chromatography using a hexane solution of 30% ethyl acetate as eluent to give 0.81 g of the target product, methyl 2-amino-6-hydroxybenzoate, in 86.6% yield. The structure of the product was confirmed by 1H NMR (DMSO-d6): δ 3.88 (s, 3H), 5.95 (d, 1H), 6.20 (d, 1H), 6.34 (s, 1H), 7.02 (t, 1H), 10.88 (s, 1H); the mass spectrum (DCI/NH3) showed m/e 168 (M + H)+.
