Reactions of N-sulfinylarylamines with 1,4-benzoquinone and 1,4-naphthoquinone: synthesis of N-aryl sulfinamoyl quinones and their hydrolysis to hydroxyquinones

Abstract

N-Sulfinylarylamines react with 1,4-naphthoquinone to give 2-(N-arylsulfinamoyl)-1,4-naphthoquinones. The reaction is believed to occur via an initial 2 + 2 cycloaddition of the NS bond of the N-sulfinylamine with 1,4-naphthoquinone, followed by fragmentation of the 1,2-thiazetidine 1-oxide intermediate with a 1,3-H shift. N-Sulfinylarylamines add regiospecifically to 5-hydroxy-1,4-naphthoquinone to give 3-(N-arylsulfinamoyl)-5-hydroxy-1,4-naphthoquinones. 1,4-Benzoquinone reacts with three molecules of N-sulfinylarylamine to give adducts. Two molecules of N-sulfinylarylamine react with 1,4-benzoquinone as in the case of 1,4-naphthoquinone and the third molecule reacts at one of the CO groups of the benzoquinone with the elimination of a molecule of SO₂. Hydrolysis of 2-(N-arylsulfinamoyl)-1,4-naphthoquinones with aqueous HCl gives 2-hydroxy-1,4-naphthoquinone.