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organic compounds
The structure of the opioid thebaine (6,7,8,14-tetradehydro-4,5-epoxy-3,6-dimethoxy-17-methylmorphinan), C19H21NO3, has been determined by single-crystal X-ray diffraction techniques at low temperature. The thebaine molecule adopts the same T-shaped conformation of the five fused rings as found in closely related rigid opioids. The geometry of the double bond at the bridgehead carbon atom is significantly distorted from planarity.