Friedel–Crafts acylation–cyclisation reactions of 3-bromophenyl ethers with phosphorus trichloride and oxalyl chloride to give the corresponding phenoxaphosphine and xanthen-9-one derivatives

Abstract

Condensations of 4-chloro- and 4-fluoro-phenyl 3-bromophenyl ether (3) with phosphorus trichloride and with oxalyl chloride in the presence of aluminium chloride gave, essentially in a one-step reaction, 7-bromo-2-chloro-phenoxaphosphine 10-oxide (4) and 6-bromo-2-fluoroxanthen-9-one (7), respectively. Best yields were obtained in dilute solutions.