Structural determination of oleanane-28,13β-olide and taraxerane-28,14β-olide fluoro-lactonization products from the reaction of oleanolic acid with SelectfluorTM.

Abstract

The X-ray crystal structure data of 12-α-fluoro-3β-hy-droxy-olean-28,13β-olide methanol hemisolvate, 2C30H47FO3·CH3OH, (1), and 12-α-fluoro-3β-hy-droxy-taraxer-28,14β-olide methanol hemisolvate, 2C30H47FO3·CH3OH, (2), are described. The fluoro-lactonization of oleanolic acid using SelectfluorTM yielded a mixture of the six-membered δ-lactone (1) and the unusual seven-membered γ-lactone (2) following a 1,2-shift of methyl C-27 from C-14 to C-13.