Chloroacetone → 2-Methylimidazo[1,2-a]pyridin-8-ol

A 1L two-necked round bottom flask containing molecular sieves (30 g, Type 4 Å) was vacuum flame-dried and cooled to room temperature. The flask was then charged with 2-amino-3-hydroxypyridine (11.2 g, 0.1 mol), chloroacetone (33.5 mL, 0.4 mol) and anhydrous methanol (400 mL) under argon. The resultant mixture was refluxed for 16 h, the molecular sieves were filtered off and the filtrate was concentrated in vacuo. The dark brown residue was dissolved in water (150 mL) and the resultant solution was extracted with diethyl ether (150 mL) and dichloromethane (2×50 mL). The dichloromethane extracts were combined and back-washed with water (20 mL). The aqueous layers were combined and adjusted to pH 10 with 40% aq NaOH, triggering precipitation of a solid. The precipitate was collected, washed successively with water (2×100 mL) and dichloromethane (100 mL), and dried over P2O5 in vacuo, giving 7.7 g (52% yield) of 8-hydroxy-2-methylimidazo[1,2-α]pyridine as a pale brown powder.

1. customflame-dried
2. filtrationthe molecular sieves were filtered off
3. concentrationthe filtrate was concentrated in vacuo
4. dissolutionThe dark brown residue was dissolved in water (150 mL)
5. extractionthe resultant solution was extracted with diethyl ether (150 mL) and dichloromethane (2×50 mL)
6. washback-washed with water (20 mL)
7. customprecipitation of a solid
8. customThe precipitate was collected
9. washwashed successively with water (2×100 mL) and dichloromethane (100 mL)
10. dry with materialdried over P2O5 in vacuo

ORD record

ord-19457dfc149d44d587d4dc4ed3be5ce6

Source dataset

uspto-grants-2006_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07105534B2