Crystal and molecular structure of subchrysine (3- O -acetylridentine), a new germacranolide from Artemisia subchrysolepis

A new sesquiterpenoid lactone was isolated from terrestrial parts of Artemisia subchrysolepis Filat. and studied by X-ray diffraction analysis and CD spectroscopy. This compound was called subchrysine and identified as (1 R ,3 S ,4 E ,6 R ,7 S )-3-acetoxy-1-hydroxygernmacra-4,10(14), 11(13)-trien-12,6-olide. Pronounced temperature dependence of the 1 H and 13 C NMR spectra of subchrysine was observed. The results of conformational analysis of subchrysine by quantum-chemical (PM3) and molecular mechanics (MMX) methods are also presented.