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. Keywords: Solar light; Photoacylation; Photooxygenation; Green chemistry e-mail: julio.benites@unap.cl INTRODUCTION Photochemical reactions carried out with sunlight are particularly interesting in the context of green chemistry due to substrate activation often occurs without additional reagents, which diminishes formation of by products, and the renewable nature of the energy source.