Synthesis, spectral, stereochemical, single crystal XRD and biological studies of 3t-pentyl-2r,6c-diarylpiperidin-4-one picrate derivatives

• The main advantages are time saving, easy workup and high yield of the product.
• Spectral and stereochemical analyses by means of 1D and 2D NMR, Mass spectral techniques and single crystal XRD.
• Piperidone ring protons are influenced by picrate anion.
• Picrate derivatives have good antimicrobial activities compared to standard drugs.

Various substituted 3t-pentyl-2r,6c-diphenylpiperidin-4-one picrates (1–7) were synthesised and characterised by elemental analysis, FT-IR and NMR spectral studies. NMR spectral assignments were made unambiguously by their one dimensional (1H NMR and 13C NMR) and two dimensional (1H–1H COSY, HSQC, HMBC, NOESY, DEPT) NMR spectra. Single crystal XRD analysis of the compound (1) has confirmed that the complex crystallized in monoclinic system with P21/n space group. The difference in the chemical shifts between equatorial methylene proton and axial proton at C(5) [Δ = δeq − δax] is highly negative in compounds 1–7 in contrast to the value observed for the corresponding parent piperidine-4-one and is indicative of the 1,3-diaxial interaction between the axial NH bond and axial hydrogen at C(5). The chemical shifts of the heterocyclic ring protons are influenced by the picrate anion. All the synthesised compounds exhibited good activity against S. aureus-Staphylococcus aureus bacterial strains and C. albicans fungal strains.

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