Synthesis of hydroxyhydrolapachol and lapachol

Abstract

Convenient syntheses of hydroxyhydrolapachol (IIa) and lapachol (I) are reported. Treatment of 2-hydroxy-1,4-naphthoquinone with succinyl peroxide gave the carboxyethyl compound (IVa) which was esterified to give the ethyl ester (IVb). Reductive acetylation of this gave a triacetate (VI) which upon treatment with methylmagnesium iodide, and oxidation of the resulting product, gave hydroxyhydrolapachol. Repeating the reductive acetylation step with hydroxyhydrolapachol followed by treatment with iodine in xylene and saponification led to lapachol.