A novel acid-catalyzed rearrangement of 9,10-diaryl-9,10- dihydroanthracene-9,10-diols affording 10,10'-diaryl-9-anthrones

Article abstract of DOI:10.1016/S0040-4020(99)00406-8

Usually, 9,10-diarylanthracenes can be obtained by reduction of the corresponding 9,10-diaryl-9,10-dihydroanthracene-9,10-diols with Kl/NaH₂PO₂ in acetic acid. In contrast, we found that in case of heteroaromatic aryl substituents and when peri substituents are present on the anthracene residue, high amounts of anthrones are formed. These anthrones can be considered to result from a vinylogous pinacol rearrangement of the initial diol. To the best of our knowledge, this type of rearrangement is rarely observed, and the 10,10'-diaryl-9-anthrones obtained in this way, are difficult to prepare otherwise. We prepared a number of such compounds and studied the mechanism of the transformation involved. The results are in agreement with a bridged transition state 10.