3-Pyridinylboronic acid → Methyl 2-amino-3-nitro-5-(3-pyridinyl)benzoate

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Reaction Steps

A stirred solution of 2-Amino-5-bromo-3-nitro-benzoic acid methyl ester (2 g, 7.27 mmol) in 1,2-dimethoxyethane (53 ml) was purged with nitrogen for 15 min and treated with aqueous sodium hydrogen carbonate solution (1M, 14.5 ml) followed by pyridine 3-boronic acid (1.33 g, 10.9 mmol) and 1,1-bis-(diphenylphosphino)ferrocene palladium (II) chloride complex (0.6 g, 0.733 mmol). The resultant mixture was boiled under reflux in a nitrogen atmosphere for 18 h. After cooling to ambient temperature, the dark mixture was diluted with saturated aqueous sodium hydrogen carbonate solution (300 ml) and extracted with ethyl acetate (3×250 ml). This was washed with brine (200 ml), dried (MgSO4) and the solvent removed in vacuo to give a residue which was purified by flash chromatography (silica) eluting with 30% to 100% ethyl acetate in 40-60 petroleum ether. The 2-Amino-3-nitro-5-pyridin-3-yl-benzoic acid methyl ester was obtained as a yellow solid (1.1 g, 56%).

Provenance & Evidence