Boron tribromide → HCID 13560308, compound

Participants

Reaction Steps

A solution of 6-methoxy-3,4-dihydrobenzopyran-7-carboxaldehyde (30.00 g, 156 mmol) in dry methylene chloride (625 mL) under nitrogen was cooled to an internal temperature of -67°. A solution of boron tribromide (1M in methylene chloride, 67.5 mL, 67.5 mmol) was added dropwise. The cooling bath was removed and the mixture allowed to stir under nitrogen for three hours. The reaction was then quenched by the dropwise addition of methanol (75 mL) and the resulting mixture poured into saturated aqueous sodium chloride (1200 mL). The layers were separated and the organic extract washed with saturated sodium chloride (600 mL), dried (Na2SO4) and concentrated to a dark solid (31.0 g). Purification by preparative HPLC (Waters Prep 500, 9:1 hexane:ethyl acetate as eluant) afforded 6-hydroxy-3,4-dihydrobenzopyran-7-carboxaldehyde (18.80 g, 67.6%), m.p. 97°-100°.

Provenance & Evidence