Table 5. Substrate Scope for Direct Oxidative Synthesis of 3-Indolylquinones from Hydroquinones Using Ag₂O/H₂O₂ and Fe₃O₄/PVP–PWA (141)^a.

^aReactions were performed with 1:1 hydroquinone/indole, 0.1 g Fe₃O₄/PVP–PWA (141), 20 mol % Ag₂O, 3 mmol H₂O₂, and 10 mL of THF at RT for 2–5 h; isolated yields after column chromatography.