Natural Furano Naphtoquinones from Lapachol: Hydroxyiso-β -Lapachone, Stenocarpoquinone-B and Avicequinone-C

This work describes cheap and simple methods to obtain biological active furano naphthoquinones in good yields. Hydroxyiso-β-lapachone (3) was obtained in 61% yield from the reaction of lapachol (1) and MCPBA in dichloromethane using Na2HPO4 as the base. Reaction of 1 with MCPBA, followed by the addition of KOH/DMSO furnished both stenocarpoquinone-A (2) and avicequinone-C (5) in 20% yield. Using oxone/acetone and NaHCO3, stenocarpoquinone-B (4) was obtained in 50% yield. The biological assays using tumor cell lines showed that 1 is, in general, less toxic than its derivatives. Compounds 4 and 5, on the other hand, were strongly active against the four tested tumor cells.