Stereochemistry of novel delta selective opiate antagonists

We have discovered novel delta selective opiate antagonists of a non-peptide nature. Our lead compound at the present time is the mixed azine between estrone and naloxone, the compound named EH-NAL. In this paper we describe the stereochemistry of EH-NAL and an EH-NAL analog, the mixed azine between pregnenolone and naltrexone, the compound named PH-NX. The stereochemical assignments are based on the high-resolution 13C-NMR studies and on the X-ray structural determinations.