Stable Quinome Methides: Regioselective Para-Oxidation of a 2,4-Bisalkylthiomethenol and Addition Reaction Reaction to Quinonemethides

The 2.4-bisfunctionalized phenol 1, a commercial antioxidant, is dehydrogenated regioselectively with potassium ferricyanide. affording the corresponding p-quinone methide 2. 1,6-Addition of nucleophiles e.g. thiols to 2 gives rise to the corresponding addition products e.g. the dithioacetals 4 of the corresponding substituted benzaldehyde. On the other hand, treatment of 2 with αα′-azoisobutyronitrile at 90°C leads to compounds 5a-b and 6, addition products of the cyanopropyl radical to the quinone methide 2. The structures of all products are confirmed mainly by 1 H-NMR-and 13 C-NMR-spectroscopy and the mode of their formation is discussed.