Ultrasound-promoted coupling of aryl and heteroaryl halides in the presence of lithium wire
摘要:
Although sonochemical reactions of bromobenzene and of 2-, 3- and 4-halogenopyridines with lithium wire in THF solution yield the expected dimers, considerable dehalogenation also occurs, as monitored by C-13-NMR spectroscopy. A pathway for the unusual formation of 4,4'-bipyridyl from the 2-halogenopyridines is proposed. No dimers were detected from the reactions with 2-bromo-4-methylquinoline and 7-bromo-2,4-dimethylquinoline. The synthetic potential of their alternative facile sonochemical dehalogenation is propounded.