Boron tribromide → HCID 57555834, compound

Participants

Reaction Steps

Boron tribromide (2.5 equivalents, 14.6 mL of 1 M solution in dichloromethane) was added dropwise to a cooled (ice bath) suspension of N-{4-[4-amino-2-(ethoxymethyl)-1H-imidazo[4,5-c]quinolin-1-yl]butyl}cyclopentanecarboxamide (2.4 g, 5.8 mmol) in dichloromethane (25 mL). The reaction mixture was allowed to slowly warm to ambient temperature and then stirred for 6 days. Additional boron tribromide (5 equivalents, 29 mmol, 29 mL) was added and the reaction was stirred at ambient until starting material was consumed. The reaction was quenched slowly with methanol (100 mL) and then concentrated under reduced pressure. The residue was combined with 6 M hydrochloric acid (100 mL), heated to 50° C., and stirred for 2 hours. The resulting solution was cooled (ice bath) and then free-based (pH 9) with the addition of 6 M aqueous sodium hydroxide. A brown gummy solid formed in the basic aqueous solution. The aqueous liquid was decanted from the solid and acetonitrile was added (30 mL). A white precipitate formed and was isolated by filtration. The white precipitate was then triturated with hot acetonitrile, allowed to cool, isolated by filtration, washed with ether, and dried under vacuum to provide N-{4-[4-amino-2-(hydroxymethyl)-1H-imidazo[4,5-c]quinolin-1-yl]butyl}cyclopentanecarboxamide (0.48 g) as a fine white solid, mp 183-186° C.; MS (ESI) m/z 382 (M+H)+; Anal. Calcd for C21H27N5O2: C, 65.35; H, 7.18; N, 18.14. Found C, 65.06; H, 6.90; N, 18.13.

Provenance & Evidence