8-epi-Salvinorin B: crystal structure and affinity at the κ opioid receptor

• Thomas A. Munro,
• Katharine K. Duncan,
• Richard J. Staples,
• Wei Xu,
• Lee-Yuan Liu-Chen,
• Cécile Béguin,
• William A. Carlezon Jr. and
• Bruce M. Cohen

Beilstein J. Org. Chem. 2007, 3, No. 1, doi:10.1186/1860-5397-3-1

• apparent above baseline noise. We separated 4a and 4b with difficulty by repeated chromatography in EtOAc/hexanes. The sample of 4a contained traces of an inseparable impurity, which if active might artificially elevate the apparent binding affinity. Since the sample showed no affinity, however, this