ANTHRACENEDIOLS AS REACTIVE DIENES IN BASE-CATALYZED CYCLOADDITIONS : REDUCTION-CYCLOADDITION REACTIONS OF ANTHRAQUINONES

Cycloadducts are formed between anthracenediols (and related aminoanthracenols) and reactive dienophiles under mild base conditions. Stronger base/protic medium can lead to a formal redox disproportionation, which is believed to occur mechanistically as a double retro-aldol reaction. The fundamental chemistry appears to be analogous to that described previously for anthrones, 2 in which base-catalyzed Diels-Alder reactions were shown to occur more rapidly than Michael additions