Chloroacetaldehyde → 5-Fluoroimidazo[1,2-a]pyridine

2-Fluoro-6-formylaminopyridine (5 g) was dissolved in 50 mL of ethanol. To the solution was added 23.5 mL (4 equivalents) of 40% chloroacetaldehyde. The mixture was stirred for one hour under reflux. The reaction mixture was gradually cooled to room temperature, to which were added a 1N—HCl aqueous solution (100 mL) and ethyl acetate (100 mL). The ethyl acetate solution was subjected to extraction with a 1N—HCl aqueous solution (100 mL×2). The aqueous solutions were combined, to which was added NaHCO3 for neutralization (pH 0.35-7.30). To the neutralized aqueous solution was added ethyl acetate (100 mL×3) to extract the product. The extract solutions were combined and dried over magnesium sulfate, which was concentrated under reduced pressure to afford 5-fluoroimidazo[1,2-a]pyridine as a black liquid product (1.5 g, yield 31%).

1. temperatureunder reflux
2. extractionThe ethyl acetate solution was subjected to extraction with a 1N—HCl aqueous solution (100 mL×2)
3. additionwas added NaHCO3 for neutralization (pH 0.35-7.30)
4. additionTo the neutralized aqueous solution was added ethyl acetate (100 mL×3)
5. extractionto extract the product
6. dry with materialdried over magnesium sulfate, which
7. concentrationwas concentrated under reduced pressure

ORD record

ord-5dbbda5cddce4608ab81745f816d308d

Source dataset

uspto-grants-2001_05

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06235731B1