A straightforward synthesis of natural oxygenatedent-kaurenoic acid derivatives

The paper presents the synthesis of some natural diterpenoids ofent-kauranic structure, starting froment-kaur-16-en-19-oic acid, a natural diterpenoid readily available from the dried wastes of sunflower (Helianthus annuusL.). The reportedent-16 alpha,17-dihydroxykauran-19-oic,ent-16 alpha-hydroxy-17-acetoxykauran-19-oic andent-16 alpha,17-diacetoxykauran-19-oic acids have been previously isolated from different plant sources and showed diverse biological activities, including anti-HIV, anti-cancer and anti-Alzheimer properties. Their chemical synthesis has not been disclosed so far. Additional cytotoxicity studies of the obtained compounds revealed a remarkable cell proliferative effect of parentent-kaur-16-en-19-oic acid and two of its synthetic derivatives, which is in line with recent pioneering studies in this area. [GRAPHICS] .