Step 2: Preparation of methyl 4-amino-2-hydroxybenzoate
In a 500 mL Parr reactor, methyl 2-hydroxy-4-nitrobenzoate (1.3 g, 6.59 mmol) was mixed with a suspension formed by 10% Pd/C catalyst (100 mg) in methanol (40 mL). The reaction mixture was shaken for 1 h under hydrogen atmosphere (30 psi). Upon completion of the reaction, the catalyst was removed by filtration through a diatomaceous earth pad and the filtrate was concentrated under reduced pressure. Methyl 4-amino-2-hydroxybenzoate was obtained as a yellow solid (1.08 g, 6.46 mmol, 98% yield). The product was analyzed by UPLC-MS showing 100% purity and the mass spectrum (MS/ESI+) showed a molecular ion peak [MH]+ of 167.9.
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