Green synthetic approaches to furoylnaphthohydroquinone and juglone

Abstract

The synthesis of two valuable precursors of biological active compounds named 2-(furan-2-yl)-1,4-dihydroxynapthohydroquinone 2 and 5-hydroxy-1,4-naphthoquinone (4, juglone) via solar photo-induced reactions from 1,4-naphthoquinone 1 and 1,5-dihydroxynaphthalene 3 in green solvent media is reported. When t-butyl alcohol and the binary t-ButOH/DMK and ternary i-PrOAc/DMK/MEK solvent mixtures were used, acylhydroquinone 2 was isolated in yields of 80, 83 and 77%, respectively. The sensitized photooxygenation of 3 "on water" and in water containing sodium dodecyl sulfate produce juglone 4 in 81 and 39% yields respectively.