Nitric Acid → 4-Bromo-3-nitrobenzoic acid

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Reaction Steps

In one method the starting quinolinone carboxylic acid 22 building block used for the synthesis of compounds comprising Formulae (I)-(X) was prepared as described in Scheme 9. The commercially available 4-bromobenzoic acid 42 was nitrated under standard conditions using fuming nitric acid to give the 4-bromo-3-nitrobenzoic acid 43 in over 95% yield. The benzoic acid 43 was coupled with ethyl acrylate 44 in the presence of palladium acetate catalyst and ligand triphenylphosphine using triethylamine as base in DMF to afford the corresponding nitro substituted benzoic acid derivative 45 in over 90% yield. The reductive cyclization of the compound 45 under hydrogenation conditions using palladium over activated carbon as catalyst under hydrogen atmosphere at around 50 psi pressure gave the quinolinone carboxylic acid 22 in over 95% yield.

Provenance & Evidence