Thermal oxygen atom transfer from benz[cd]indazole 1,2-dioxide to benzenoid derivatives

Abstract

Thermolysis of benz[cd]indazole 1,2-dioxide at 105–110 °C in the presence of various benzenoid derivatives gave benz[cd]indazole 1-oxide and oxidation products of the benzenoid substrates. Toluene was oxidised to benzyl alcohol (40% yield based on the dioxide), benzaldehyde (19%), benzoic acid (0.5%), o-cresol (11%), m-cresol (3%), and p-cresol ([graphic omitted]4%); an experiment with [4-³H]toluene showed no appreciable migration and retention of tritium (NIH shift) during formation of p-cresol. [4-²H]Anisole was converted mainly into deuteriated phenol (14%) and 2-hydroxyanisole (13%) together with 4-hydroxyanisole (4%) containing no significant amounts of deuterium. Naphthalene gave α- and β-naphthol in low yield. In contrast, 4-methylcinnoline 1,2-dioxide was stable in hot anisole. The results are compared with those reported for other, related oxidising systems.