Total synthesis and structure elucidation of (±)-triumphalone and (±)-isotriumphalone

The first total synthesis of (+/-)-triumphalone has been achieved in 8 steps from phloroglucinol. Synthetic triumphalone was converted to (+/-)-isotriumphalone in one step by the alpha-ketol rearrangement in a highly efficient manner. Although NMR data of the synthetic isotriumphalone were identical to the reported data, the X-ray crystallographic data did not support the proposed structure of isotriumphalone, but the cyclopentanone structure bearing the cis-diol moiety. We found that the rearrangement reaction smoothly took place in a protic solvent under thermal reaction conditions. (C) 2014 Elsevier Ltd. All rights reserved.