Untersuchungen an 1,4-Naphthochinonen, 25. Mitt. Reaktion des Redox 5-Lipoxygenase-Inhibitors 2-(3,5-Di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthochinon mit O2•− und 3O2

1,4-Naphthoquinones, XXV: Reaction of the Redox 5-Lipoxygenase Inhibitor 2-(3,5-Di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthoquinone with O₂^?? and ³O₂ The 5-lipoxygenase inhibitor 2-(3,5-di-tert-butyl-4-hydroxyphenyl)-3-hydroxy-1,4-naphthoquinone ( 2 ), its deoxygenation product 1 as well as the oxygenated species 3 are O₂^?? quenchers with different power in aqueous solution. In alcoholic solution the antioxidative capacity of 1 does not change, 2 indeed is still only a weak O₂^?? quencher while 3 shows prooxidative properties. This phenomenon was explored in the O₂^?? generating oxygenation system (OS) DMSO-CO₃^2-–O₂ by preparative techniques. The following reaction sequence could be proven: 3 ? 2 ? 4 (2,6-di-tert-butyl-1,4-benzoquinone). While the step 3 ? 2 would be O₂^?? dependent the transition 2 ? 4 occurs on two levels: 1. retro Michael reaction with release of 2,6-di-tert-butylphenol ( 5 ), 2. base catalysed oxygenation of 5 ? 4 by ³O₂. The diphenoquinone 6 occurring as byproduct is split with the OS – in contrast to the reaction with ¹O₂ – in considerable yield to give 4 .