Ethyl chloroformate → Ethyl 6-bromoimidazo[1,2-a]pyridine-3-carboxylate

Temperature

0 °C

A mixture of 9.69 g 6-bromo-3-iodoimidazo[1,2-a]pyridine (compound in Production Example 49) and 450 mL anhydrous tetrahydrofuran was added little by little to 4.5 mL isopropyl magnesium bromide (0.75 M tetrahydrofuran solution) under ice-cooling in a stream of nitrogen. Then, this reaction solution was returned to room temperature and stirred for 1.5 hours. The reaction solution was cooled to −60° C. or less in a dry ice/acetone bath, 50 mL solution of 4.5 mL ethyl chlorocarbonate in anhydrous tetrahydrofuran was added dropwise thereto over 30 minutes, and the temperature of the reaction solution was increased to 0° C. After saturated sodium bicarbonate was added to the reaction solution, ethyl acetate and water were added thereto, and the organic layer was separated. The aqueous layer was saturated with common salt and then extracted with ethyl acetate. The combined organic layer was washed with brine and then dried over anhydrous sodium sulfate. The drying agent was filtered off, and the filtrate was evaporated. The resulting residue was purified by NH silica gel column chromatography (ethyl acetate/hexane) to give 5.09 g of the title compound as white crystals.

1. temperaturecooling in a stream of nitrogen
2. customwas returned to room temperature
3. temperatureThe reaction solution was cooled to −60° C. or less in a dry ice/acetone bath
4. waitover 30 minutes
5. additionwere added
6. customthe organic layer was separated
7. extractionextracted with ethyl acetate
8. washThe combined organic layer was washed with brine
9. dry with materialdried over anhydrous sodium sulfate
10. filtrationThe drying agent was filtered off
11. customthe filtrate was evaporated
12. customThe resulting residue was purified by NH silica gel column chromatography (ethyl acetate/hexane)

ORD record

ord-0bdc1355248043108d099b572644b3e7

Source dataset

uspto-grants-2006_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07074801B1