title: Fentanyl and its analogue N-(1-phenylpyrazol-3-yl)-N-[1-(2-phenylethyl)-4-piperidyl]propanamide: 1H- and 13C-NMR spectroscopy, X-ray crystallography, and theoretical calculations.
abstract: The oxalate salts and free bases of fentanyl and N-[1-(2-phenylethyl)-4-piperidyl]-N-(1-phenyl-4-pyrazolyl)propanamide, a new lead compound for long-acting analgesia, have been characterized by (1)H- and (13)C-NMR spectroscopy. The crystal structure of the hydrochloride of N-[1-(2-phenylethyl)-4-piperidyl]-N-(1-phenyl-4-pyrazolyl)propanamide monohydrate has been determined. Two centrosymmetrically related cations, joined through C(phenyl)-H em leader pi contacts, encapsulate a large void that contains pairs of anions and bridged water molecules into a zero-dimensional (0D) supramolecular motif. The cations are linked to this framework via N(+)H em leader Cl(-) contacts. GIAO/B3LYP calculations have been carried out to compare the experimental (13)C chemical shifts with the absolute shieldings thus calculated. The protonation of both molecules takes place on the piperidine ring (axial protonation), as has been verified both in the solid state (X-ray) and in solution (NMR).
authors.affiliation: Instituto de Química Médica, Consejo Superior de Investigaciones Científicas, Juan de la cierva, Madrid, Spain.
authors.forename: María Luisa
authors.initials: ML
authors.lastname: Jimeno
authors.forename: Ibon
authors.initials: I
authors.lastname: Alkorta
authors.forename: Carolina
authors.initials: C
authors.lastname: Cano
authors.forename: Nadine
authors.initials: N
authors.lastname: Jagerovic
authors.forename: Pilar
authors.initials: P
authors.lastname: Goya
authors.forename: José
authors.initials: J
authors.lastname: Elguero
authors.forename: Concepción
authors.initials: C
authors.lastname: Foces-Foces
mesh_terms: D002250:Carbon Radioisotopes; D018360:Crystallography, X-Ray / Q000379:methods; D005283:Fentanyl / Q000031:analogs & derivatives* / Q000737:chemistry; D008956:Models, Chemical; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D011720:Pyrazoles / Q000737:chemistry
chemical_list: D002250:Carbon Radioisotopes; D011522:Protons; D011720:Pyrazoles; D005283:Fentanyl