Application of the Homonuclear Internuclear Double Resonance Technique in the Triterpene Field. II. Assignments of Methyl Resonances of Triterpenes related to Friedelin

Abstract

The homonuclear internuclear double resonance (INDOR) technique in combination with the pseudo-contact shift method was applied to several triterpenes related to friedelin, and the methyl resonances of these triterpenes were assigned. The results suggest that rings D and E of friedelin in solution are in a boat form.