Efficient synthesis of the first betulonic acid-acetylene hybrids and their hepatoprotective and anti-inflammatory activity

The Sonogashira reaction can be applied for the preparation of acetylenic derivatives of betulonic acid where the triterpenoid moiety can serve as either the halo- or the acetylenic component. This reaction opened access to the first derivatives of betulonic acid containing either the arylethynyl (C equivalent to C-Ar(Het) or the ethynyl (C equivalent to CH) moieties. From the fundamental perspective, this work illustrates the possibility of selective Pd-catalyzed cross-coupling at terminal acetylenes in the presence of a terminal alkene. Hepatoprotective and anti-inflammatory properties of selected acetylenic derivatives of betulonic acid were investigated using the CCl4-induced hepatitis and carrageenan-induced edema models, respectively. (C) 2009 Elsevier Ltd. All rights reserved.