Total Synthesis of Ouabagenin and Ouabain

The highly oxygenated steroid ouabagenin (1 b) and its glycoside ouabain (1 a) were prepared by a strategy based on a polyanionic cyclization. Starting building blocks A and B were combined to give the key intermediate C and transformed into 1 b in 27 steps. Finally, ouabagenin (1 b) was converted into ouabain (1 a) in six steps (see scheme). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2008/z704959_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.