L-Proline → 1,8-Naphthyridine, 2-methyl-

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Reaction Steps

To a solution of 2-amino-3-pyridinecarboxaldehyde (from step c, 24.57 g) in acetone (750 mL) was added proline (2.3 g, 20 mmole), then the mixture was heated to reflux. After 48 hr the mixture was cooled to RT, filtered, and concentrated. Flash column chromatography on silica gel (35% acetone/hexanes) gave the title compound (18.5 g, 64% over 3 steps) as an orangish-yellow solid: 1H NMR (300 MHz, CDCl3) δ 9.07 (m, 1 H), 8.10 (m, 2H), 7.40 (m, 2H), 2.80 (s, 3H); MS (ES) m/e 145 (M+H)+.

Provenance & Evidence