Manganese-Catalyzed Synthesis of Quaternary Peroxides: Application in Catalytic Deperoxidation and Rearrangement Reactions

Abstract

Highly efficient, selective and direct C-H peroxidation of 9-substituted fluorenes has been achieved using Mn-2,2’-bipyridine-catalyst via radical-radical cross-coupling. Moreover, this method effectively promote the vicinal bis-peroxidation of sterically hindered various substituted arylidene-9H-fluorene/arylideneindolin-2-one derivatives to afford highly substituted bisperoxides with high selectivity over the oxidative cleavage of C=C bond that usually form ketone of aldehyde. Furthermore, a new approach for the synthesis of (Z)-6-benzylidene-6H-benzo[c]chromene has been achieved via an acid-catalyzed skeletal rearrangement of these peroxides. For the first time, unlike O-O bond cleavage, reductive C-O bond cleavage in peroxides using Pd-catalyst and H2 is described which enables the reversible reaction to afford exclusively deperoxidised products. A detailed mechanism for peroxidation, molecular rearrangement and deperoxidation has been proposed with preliminary experimental evidences.