Sulfuric Acid → 2-Methyl-1,5-naphthyridine

Participants

Reaction Steps

A mixture of concentrated sulfuric acid (14 mL), boric acid (1.55 g, 39 mmol), sodium m-nitrobenzenesulfonate (11.30 g, 50 mmol), and iron sulfate heptahydrate (0.90 g, 3.23 mmol) was stirred at room temperature. Glycerol (8 mL) was added to the mixture followed by 3-amino-6-picoline (2.79 g, 25 mmol) and water (14 mL). The mixture was heated at 135° C. for 18 h. The reaction mixture was cooled to room temperature, basified using 4 N aqueous sodium hydroxide to pH 8, and extracted with EtOAc (50 mL×3). The organic extracts were combined, concentrated, and the residue was purified by column chromatography to afford 2-methyl-1,5-naphthyridine (2.01 g) as a light brown crystalline solid. MS (ESI): m/z 145 [M+H]+. See, e.g., J. Med. Chem. 2004, 47, 4494-4506.

Provenance & Evidence