Ammonium formate → 5-Amino-biphenyl-2-carboxylic acid methyl ester

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Reaction Steps

A mixture of the 2-phenyl-4-nitrobenzoic acid methyl ester prepared in Example 210A (48.4 g, 188 mmol), palladium (10%) on carbon (2.1 g), and ammonium formate (59.4 g, 941 mmol) in methanol (500 mL) was refluxed for 3 hours. The solvent was removed in vacuo, and the residue was desolved in a miminum amount of hot methanol (about 30 mL). To this solution was added chloroform and ether (1/1 ratio, 400 mL), and the mixture was filtered through a plug of silica gel (80 g) and rinsed with chloroform. The filtrate was concentrated in vacuo to give pure 2-phenyl-4-aminobenzoic acid methyl ester (42.4 g, 99%). 1H NMR (300 MHz, CDCl3) δ 7.80 (d, 1H), 7.40-7.25 (m, 5H), 6.65 (dd, 1H), 6.57 (d, 1H), 3.60 (s 3H).

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