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 δH(N) protons. Whereas, the chemical shift for 13C NMR analysis for C=O and C=S presence at δC 169-179 ppm. The significant stretching bands for ν(N-H), ν(C=S), ν(C=O) and ν(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). Show more