Rare derivatives of dehydroiso-alpha-lapachone, 3-hydroxydehydroiso-alpha-lapachone (1) and 3,8-dihydrox-ydehydroiso- alpha-lapachone (2) along with 5-hydroxydehydroiso-alpha-lapachone, 5-methoxy-dehydroisoa-alpha-lapachone, and 8-methoxy-dehydroiso-alpha-lapachone were isolated from a chloroform extract of the heartwood of Heterophragma adenophyllum (Bignoniaceae). A reinvestigation of the structures of 1 and 2 using NMR spectroscopic analysis and Mosher's method, combined with a vibrational circular dichroism (VCD) method and X-ray analysis for 1, indicated that the cis-orientation of the isopropenyl and OH groups originally assigned for 1 and 2 needs to be revised to the trans-orientation. Furthermore, the previously assigned R configuration at C-3 of 1 and 2 must be corrected as the S configuration. (C) 2014 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.