Syntheses of potent Leu-enkephalin analogs possessing β-hydroxy-α,α-disubstituted-α-amino acid and their characterization to opioid receptors

Syntheses of potent Leu-enkephalin analogs possessing β-hydroxy-α,α-disubstituted-α-amino acid and their characterization to opioid receptors Synthesis and Biological Activities of Cyclic Lanthionine Enkephalin Analogues:  δ-Opioid Receptor Selective Ligands Enkephalin analogues with 2′,6′-dimethylphenylalanine replacing phenylalanine in position 4 Synthesis and pharmacological characterization in vitro of cyclic enkephalin analogs: effect of conformational constraints on opiate receptor selectivity Cyclic Enkephalin Analogues with Exceptional Potency and Selectivity for δ-Opioid Receptors [L-Ala3]DPDPE: A New Enkephalin Analog with a Unique Opioid Receptor Activity Profile. Further Evidence of .delta.-Opioid Receptor Multiplicity Opioid activity of 4-imidazolidinone positional analogues of Leu-Enkephalin Cyclic enkephalin analogs with exceptional potency at peripheral .delta. opioid receptors Cyclic enkephalin analog containing .alpha.-amino-.beta.-mercapto-.beta.,.beta.-pentamethylenepropionic acid at position 2 or 5 New potent enkephalin analogs containing trifluoromethylamino acid residues