Synthesis and crystal structures of five fluorinated diphenidine derivatives

Diphenidine (1a), a dissociative anaesthetic, was first reported in 2013. Since then, a number of derivatives e.g. 2-methoxphenidine (1b) have been produced by clandestine laboratories and sold as research chemicals. Fluorinated diphenidines, namely, [1-(2,6-difluorophenyl)-2-phenylethyl]dimethylaza...

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Main Authors: Ryan E. Mewis, Matthew C. Hulme, Jack Marron, Stuart K. Langley, Oliver B. Sutcliffe, Sophie L. Benjamin
Format: Article
Language:English
Published: International Union of Crystallography 2025-03-01
Series:Acta Crystallographica Section E: Crystallographic Communications
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Online Access:https://journals.iucr.org/paper?S2056989025001288
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Summary:Diphenidine (1a), a dissociative anaesthetic, was first reported in 2013. Since then, a number of derivatives e.g. 2-methoxphenidine (1b) have been produced by clandestine laboratories and sold as research chemicals. Fluorinated diphenidines, namely, [1-(2,6-difluorophenyl)-2-phenylethyl]dimethylazanium chloride, C16H18F2N+·Cl−, (I), [1-(2,6-difluorophenyl)-2-phenylethyl](ethyl)azanium chloride dichloromethane hemisolvate, 2C16H18F2N+·2Cl−·CH2Cl2, (II), tert-butyl[1-(2,6-difluorophenyl)-2-phenylethyl]azanium chloride, C18H22F2N+·Cl−, (III), 1-[1-(2,6-difluorophenyl)-2-phenylethyl]pyrrolidin-1-ium chloride, C18H20F2N+·Cl−, (IV), and 1-[1-(2,3,4,5,6-pentafluorophenyl)-2-phenylethyl]piperidin-1-ium chloride, C19H19F5N+·Cl−, (V), were synthesized and structurally characterized by 1H, 13C and 19F NMR spectroscopy, and single-crystal X-ray diffraction. All five structures exhibit hydrogen bonding between the quaternary amine hydrogen atoms and the chlorine. The N—H...Cl distances for (II) and (III) range from 2.21 to 2.31 Å, whereas (I), (IV) and (V) exhibit shorter N—H...Cl distances (2.07–2.20 Å). Compounds (IV) and (V) include pyrrolidine and piperidine rings, respectively; the pyrrolidine ring adopts an envelope conformation whereas the piperidine ring adopts a chair conformation. The crystal packing in compounds (I)–(V) is characterized by C—H...π interactions; no π–π interactions are observed.
ISSN:2056-9890