Opiate receptor binding properties of morphine-, dihydromorphine-, and codeine 6-O-sulfate ester congeners

A series of 3-O-acyl-6-O-sulfate esters of morphine, dihydromorphine, N-methylmorphinium iodide, codeine, and dihydrocodeine were prepared and evaluated for their ability to bind to μ-, δ-, κ1-, κ2-, and κ3-opiate receptors. Several compounds exhibited good affinity for the μ-opiate receptor. Morphine-3-O-propionyl-6-O-sulfate had four times greater affinity than morphine at the μ-opiate receptor and was the most selective compound at this receptor subtype.