Synthetic analgesics. Synthesis and pharmacology of the diastereoisomers of N-[3-methyl-1-(2-phenylethyl)-4-piperidyl]-N-phenylpropanamide and N-[3-methyl-1-(1-methyl-2-phenylethyl)-4-piperidyl]-N-phenylpropanamide
Willem F. M. Van Bever, Carlos J. E. Niemegeers, Paul A. J. Janssen;

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(https://www.thevespiary.org/rhodium/Rhodium/pdf/fentanyl/3-methylfentanyl.diastereomers.pdf)

Abstract: The synthesis of the respective diastereoisomers and enantiomers of N-[3-methyl-1-(2-phenylethyl)-4-piperidylj-N-phenylpropanamide and N-[3-methyl-l-(l-methyl-2-phenylethyl)-4-piperidyl]-N-phenylpropanamide is reported. Analgesic activity is evaluated in the tail withdrawal test in rats. cis-(+)-N-[3-Methyl-l-(2-phenylethyl)-4-piper-idyll-N-phenylpropanamide (23) is found to be an extremely potent analgesic, up to 6684 times morphine. Compound 23 has a fast onset of action, a shorter duration of action than morphine, and an unusually high safety margin.

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