Hydrogen Bromide → 6-Bromo-8-methylimidazo(1,2-a)pyridine

関与物質

反応条件

反応手順

To a solution of commercially available 2-amino-5-bromo-3-picoline (21.48 g, 115 mmol) and bromoacetaldehyde diethyl acetal (90%, 39.6 mL, 230 mmol) in EtOH (110 mL) was added 48% aq. HBr (11 mL) and the mixture was refluxed for 11 h. Cooled to 23° C., diluted with EtOAc, poured into sat. NaHCO3-sol., separated phases, washed with the organic layer with brine, dried over Na2SO4. Removal of the solvent in vacuum (not over 40° C. bath temperature) left an orange liquid, which was directly coated on silica gel for chromatography. Silica gel column filtration with heptane/EtOAc 50:50->0:100 gave the title compound as a light brown solid (17.36 g, 72%). MS (ISP) 211.0 [(M+H)+], 231.1 [(M+2+H)+].

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