Öz The crystal structure of 3-epicaryoptin has been determined from single-crystal X-ray data. The crystals are monoclinic, with unit-cell dimensions a = 7.876 (1), b = 17.278 (1), c = 9.697(1) Â, (3=100.24(1)°, space group P2p and z=2. The structure was solved by direct methods and refined by full-matrix least squares. For the correct enantiomer, R = 0.053 for the 2605 indepen- dent diffractometer measured reflections.