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The general procedure for the synthesis of 6-bromopyrido[2,3-d]pyrimidin-4(1H)-ones from formamidine acetate and 2-amino-5-bromobenzoic acid was as follows: formamidine acetate (1 eq.) was added to a 1.2 M solution of 2-amino-5-bromobenzoic acid (1 eq.) in N,N-dimethylformamide. The reaction mixture was heated to reflux and stirred at this temperature for 16 hours. Upon completion of the reaction, the mixture was cooled to room temperature, followed by the slow addition of a 5% aqueous NaHCO3 solution (3 volumes) with vigorous stirring. The resulting precipitate was collected by filtration and washed sequentially with water (2 x 1 volume) and tert-butyl methyl ether (2 x 1 volume). Finally, the product was dried in a vacuum oven to afford 6-bromopyrido[2,3-d]pyrimidin-4(1H)-one without further purification. The product yield was 91% and LC-MS analysis showed m/z of 225 [M-H]? and retention time of 2.31 min.