Bromochloromethane → HCID 86657996, compound

Participants

Reaction Steps

2.5 g of bromochloromethane (18.8 mmol) were added at room temperature to a solution of 2.0 g of crude (S)-6-Fluoro-1-benzopyran-2-carboxylic acid methyl ester, obtained after separation of the corresponding racemic mixture on a chiral chromatography column (9.4 mmol, 87.9% A, ee>99%), in 40 ml THF. The solution was then cooled to −80/−85° C. and 7.7 ml of 2.5 M n-BuLi in hexane (19 mmol) were slowly added to maintain the internal temperature between −75° C. and −80° C. The reaction progress was monitored by TLC. The solution was then acidified by the addition of 2 ml glacial acetic acid in 2 ml THF between −70° C. and −80° C. 10 ml of water were then added at −20/0° C. and the aqueous layer was then removed after decantation. The organic layer was concentrated under reduced pressure to give the title compound (2.54 g) as a yellow oil (ee: 99%, 94.8% A).

Provenance & Evidence