Abstract
THE CRYSTAL STRUCTURE OF THE TITLE COMPOUND [SYSTEMATIC NAME: 5,6,10-trihydr-oxy-7-isopropyl-1,1,4a-trimethyl-2,3,4,4a-tetra-hydro-phenanthren-9(1H)-one], C(20)H(26)O(4), has been reported previously [Salae et al. (2009 ▶). Acta Cryst. E65, o2379-o2380], but the absolute configuration could not be determined as there was no significant anomalous dispersion using data collected with Mo radiation. The absolute configuration has now been determined by refinement of the Flack parameter with data collected using Cu radiation. The absolute configuration at position 4a of the diterpenoid is (R)-methyl; other features of the mol-ecule and its crystal packing are similar to those previously described.