Synthesis, Spectral and Single-Crystal Analyses of New Derivatives of 4-Amino-N-benzylpiperidine

Abstract

Two new compounds of thiourea derivatives of cinnamoyl and benzoylisothiocyanate with 4-amino-N-benzylpiperidine have been successfully synthesized. The new molecules, 1-(1-benzylpiperidine-4-yl)-3-benzoyl thiourea (I) (yield 83 %) and 1-(1-benzylpiperidine-4-yl)-3-(3-phenylacryloyl)thiourea (II) (yield 81%) were characterized by NMR, IR, UV, CHNS-O techniques as well as X-ray diffraction for single crystal. ¹H NMR spectra show chemical shift at 10.77-10.80 ppm and 8.98-8.93 ppm were assigned for both dH(N) protons. Whereas, the chemical shift for ¹³C NMR analysis for C=O and C=S presence at dC 169-179 ppm. The significant stretching bands for n(N-H), n(C=S), n(C=O) and n(C-N) were around 3250, 800, 1650 and 1340 cm^-1, respectively. The important chromophore of C=O was observed with a maximum absorption at around 300 nm in the UV spectra. The structures of (I) and (II) were determined via X-ray diffraction analysis for single crystal. Both molecules exhibit monoclinic crystal system and adopt trans-cis configuration with respect to the position of the phenyl and N-benzylpiperidine groups relative to the thione S atom, across their C-N bonds. There is one intramolecular N-H···O hydrogen bonds in both molecules that lead to the formation of pseudo-six-membered, in addition to a pseudo-five-membered ring, C9–H9···S1, in (I) which stabilizes the molecule. In the crystal lattice, the molecules are linked by intermolecular hydrogen bonds C–H···S and C–H···O forming chain network in (I) and polymeric in (II).