Separation of New Naphthoxazole Derivatives of Lapachol by High-Speed Counter-Current Chromatography

Abstract

This work describes the use of high-speed counter-current chromatography as an efficient and economic method in the separation and purification of new naphthoxazolic heterocyclic derivatives from lapachol (1), a naturally occurring naphtoquinone from different species of Tabebuia. A series of naphthoxazoles was obtained by nucleophilic condensation of lapachol (1) with aromatic aldehydes in ammonium medium. Each reaction led to the formation of two main products, derivatives from β-xyloidone, and the naphthoxazoles with the isoprenyl side chain of lapachol (1). Reaction products were purified by counter-current chromatography, using hexane–acetonitrile–methanol (2:2:1, v/v/v) as a non-aqueous solvent system.