13C NMR STUDIES OF SOME COMPLEX NATURAL OXYGEN HETEROCYCLICS. STRUCTURE OF MILLETTIN, A NOVEL ISOFLAVONE ISOLATED FROM MILLETTIA AURICULATA

Article abstract of DOI:10.1016/S0040-4020(01)97667-7

13C NMR spectra for a variety of isoflavones are presented and analysed.The novel isoflavone, Millettin (Xa) is shown to be closely related to Auriculatin (II).While comparison of the 13C NMR spectra did not readily prove the orientation of the fused pyran ring, the use of acetylation shifts showed unambiguously that the fusion in linear, rather than angular.