Stereoselective formation and rearrangements of naphthalen-2(1H)-one epoxides

Abstract

Epoxidation of 1-hydroxy-1-isopropylnaphthalen-2(1H)-one (1) with alkaline hydrogen peroxide occurs exclusively from the face trans to the hydroxy-group. The epoxide (2) is isomerised in mild base by a ketol rearrangement and epoxide ring opening to r-2,3-epoxy-3,4-dihydro-t-4-hydroxy-2-isqpropylnaphthalen-1(2H)-one (3); stronger bases produce 2-isopropylnaphthoquinone and 1,4-dihydroxy-1-isopropylnaphthalen-2(1H)-one (5). Treatment of the epoxide (1) with acetic acid yields 2-hydroxy-2-isopropylnaphthalene-1,3(4H)-dione (10). The acetoxy-epoxide (15) obtained analogously and stereospecifically from 1-acetoxy-1-isopropylnaphthalen-2(1H)-one rearranges in acetic acid to 1-acetoxy-3-hydroxy-1-isopropylnaphthalen-2(1H)-one (16).