Acetic Acid → 4-(Methylthio)-2-(pyridin-3-yl)thiazol-5-amine

Participants

Reaction Steps

To a nitrogen-purged solution of 4-(methylthio)-5-nitro-2-(pyridin-3-yl)thiazole (253 mg, 1 mmol) in ethyl acetate (50 mL) in a Parr bottle were added glacial acetic acid (601 mg, 10 mmol), followed by Pd on carbon (35 mg, 10% (w)). Hydrogen was added and the mixture was shaken in a Parr shaker for 2 hours and filtered through a bed of Celite®. The filtrate was concentrated under vacuum to give 4-(methylthio)-2-(pyridin-3-yl)thiazol-5-amine as a pale yellow solid, which was placed under high vacuum to remove residual acetic acid. This crude was found to be 95% pure by GC-MS. The crude 4-(methylthio)-2-(pyridin-3-yl)thiazol-5-amine was used without further purification to prepare 3-(methylthio)-N-(4-(methylthio)-2-(pyridin-3-yl)thiazol-5-yl)propanamide. To a solution of 4-(methylthio)-2-(pyridin-3-yl)thiazol-5-amine (100 mg, 0.45 mmol) in methylene chloride (2 mL) were added dimethylaminopyridine (137 mg, 1.12 mmol) followed by 3-(methylthio)propanoyl chloride (68 mg, 0.49 mmol). The mixture was stirred at room temperature for 30 min. The mixture was diluted with dichloromethane (10 mL) and water (5 mL). The organic phase was separated, rinsed with brine, dried over MgSO4 and concentrated in vacuo to give a yellow solid. This solid was purified by silica gel chromatography (methylene chloride-methanol) to give 3-(methylthio)-N-(4-(methylthio)-2-(pyridin-3-yl)thiazol-5-yl)propanamide as a yellow solid (32 mg, 22%): mp 72-74° C., 1H NMR (300 MHz, DMSO-d6) δ 10.90 (s, 1H), 9.08 (m, 1H), 8.64 (d, J=4.8 Hz, 1H), 8.32 (d, J=9.0 Hz, 1H), 7.57 (dd, J=5.1 Hz, 8.4 Hz, 1H), 3.25 (s, 3H), 2.85 (m, 2H), 2.73 (m, 2H), 2.07 (s, 3H); ESIMS m/z 326.1(M+1), 324.1 (M-1).

Provenance & Evidence