Probes for narcotic receptor mediated phenomena .24. Synthesis, single crystal X-ray analyses, in vitro and in vivo properties of 6 alpha- and 6 beta-iodo-3,14-dihydroxy-17-methyl-4,5 alpha-epoxymorphinans

The 6 alpha- and 6 beta-iodo-3,14-dihydroxy-17-methyl-4,5 alpha-epoxymorphinans, potential SPECT ligands, were synthesized and found to be mu-selective opioids, more potent in vitro and in vivo than their 6-hydroxy relatives. Single-crystal analysis showed that the 6 alpha- and 6 beta-iodine atoms are spatially closely located although the C-ring conformations of these compounds are quite different (twist-boat form vs. chair). These epimeric conformational differences were not reflected in their binding affinities.