Mixed κ agonists and μ agonists/Antagonists as potential pharmacotherapeutics for cocaine abuse: synthesis and opioid receptor binding affinity of N-substituted derivatives of morphinan

A series of new N-substituted derivatives of morphinan was synthesized and their binding affinity for the three opioid receptors (μ, δ, and κ) was determined. A paradoxical effect of N-propargyl (MCL-117) and N-(3-iodoprop-(2E)-enyl) (MCL-118) substituents on the binding affinities for the μ and κ opioid receptors was observed. All of these novel derivatives showed a preference for the μ and κ versus δ binding.