Calcium Carbonate → 5-Iodo-6-methyl-4-oxo-1,4-dihydropyridine-3-carboxylic acid

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Reaction Steps

To 6-methyl-4-(1H)-pyridone-3-carboxylic acid (prepared according to the procedure described in J. Org. Chem., 1972, 37, 1145-1148) (10.0 g, 65.4 mmol) and calcium carbonate (6.55 g, 65.4 mmol) in N,N-dimethylformamide (100 ml) was added iodine monochloride (21.2 g, 130.8 mmol) in N,N-dimethylformamide (20 ml). After 6 hours sodium bisulfite solution (30 ml) was added and the solution poured into ice water (500 ml). The precipitate was collected by filtration washing with water and methanol to give a cream coloured solid (15.7 g, 86%). 1H NMR (250 MHz, DMSO-d6) δ15.42 (1H, br s), 13.33 (1H, br s), 8.50 (1H, s), 2.60 (3H, s); MS (ES+) m/z 280 [MH]+.

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