Radical rearrangements of 1,3-dimethylindene derivatives: a comparison with rearrangement by 1,5-sigmatropy

Abstract

Radical dissociation-recombination mechanisms are proposed for the following thermal reactions : (i) interconversion of the meso- and (±)-forms of the bi-indenyls (3) and (6), (ii) racemisation of the methyl ether (1; X = Ph₃COMe), and (iii) diastereoisomerisation of the optically active semithioacetals (10). The characteristics of these reactions stand in contrast to those of similar reactions following a concerted path.