The first enantiomeric pair of irreversible opioid ligands [(+)-and (-)-41 were synthesized in> 99.6% optical purity as determined by HPLC analysis of diastereoisomeric derivatives of the intermediate 3-methyl-N-phenyl-4-piperidinamine (9) enantiomers. Single-crystal X-ray analysis of the (R, R)-L-(+)-tartaric acid salt of (-)-9 revealed the absolute configuration to be 3S, 4R. The absolute configuration of (-)-3 [cis-(-)-3-methylfentanyl] and (-)-4 derived from ...
