Tandem Oxidative Dearomatizations of Diphenylanthracene Atropisomers.

The first examples of tandem oxidative dearomatizations of 9,10-diphenylanthracene atropisomers with ,'- formyl substituents are presented. In the presence of KMnO, their stereoselective tandem double oxidation and spirocyclization mainly afford the or dearomatized 9,10-diphthalide anthracenes. Using Pinnick's reagent and depending on the conditions, the oxidation can mainly lead to the corresponding or diacids in good yields or to three oxidation products.