2-Bromopropane → 8-Isopropoxy-[1,6]naphthyridine-7-carboxylic acid methyl ester

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Reaction Steps

2-Bromopropane (0.9 mL) was added to a stirred mixture of 8-hydroxy-[1,6]naphthyridine-7-carboxylic acid methyl ester (prepared according to Anthony and coworkers, Patent WO 02/30931 A2) (1.00 g, 4.90 mmol), K2CO3 (2.79 g) and DMSO (15 mL). After 40 h at 50° C., sat'd NH4Cl (20 mL) was added and the mixture extracted with dichloromethane (10 mL×3). The extracts were combined and concentrated. Diethyl ether (40 mL) was added to the residue and the resulting mixture washed successively with H2O (5 mL×2) and brine (10 mL), and dried. Solvent removal gave 8-isopropoxy-[1,6]naphthyridine-7-carboxylic acid methyl ester (1.06 g, 88%).—1H NMR (CDCl3): δ 9.16 (dd, J=1.9 and 4.3, 1H), 9.03 (s, 1H), 8.34 (dd, J=1.9 and 8.5, 1 H), 7.63 (dd, J=4.3 and 8.5, 1H), 5.33 (sep, J=6.2, 1H), 4.04 (s, 3H), 1.42 (d, J=6.2, 6H).

Provenance & Evidence