Boron tribromide → HCID 20504347, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of methyl 4-(bromomethyl)-5-(4-chloro-2-methoxybenzoyl)-1-methylpyrrole-2-carboxylate (0.45 g, 0.0011 m) in dry methylene chloride (20 ml) at dry-ice/acetone bath temperature was added boron tribromide (1.3 ml of a 1.0 M solution in methylene chloride) all at once. After 2 hours at these temperatures, the reaction mixture was allowed to warm to 0° C. and kept in a wet-ice bath for an additional 4 hours. Methylene chloride (30 ml) was added, followed by 50 g of ice-water. The mixture was separated, the methylene chloride layer dried and concentrated to crude methyl 4-(bromomethyl)-5-(4-chlorosalicyloyl)-1-methylpyrrole-2-carboxylate which was subsequently dissolved in dry N,N-dimethylformamide (25 ml), stirred and cooled to about -50° C. before sodium hydride (57% suspension in mineral oil, 0.07 g) was added all at once. After 10 minutes, the dry-ice bath was replaced by a wet-ice bath for 2 hours, and the reaction mixture then allowed to rise to room temperature. After 1 hour, excess ether was added, followed by ice-water. The ether layer was separated, dried over sodium sulfate, and concentrated to a white solid. Trituration with hexane yielded methyl 7-chloro-4,10-dihydro-1-methyl-10-oxo-1H[1]benzoxepino[4,3-b]pyrrole-2-carboxylate as a white solid, m.p. 169°-170° C.

Provenance & Evidence