Synthesis, characterization, stereochemistry and antibacterial activity of N-acyl-2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonanes

•Three compounds were synthesized and the conformational analysis was carried out.•Acylation of diazabicyclo[3.3.1]nonane induces a change in conformation.•Compounds prefer twin chair conformation with partial flattening at nitrogen end.•X-ray crystal structure for the N-dichloroacetyl compound has been solved.•Antibacterial activity assay has also been performed.

Three new N-acyl-2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonanes 3–5 have been synthesized. The structural characterization and the conformational preferences of the compounds 3–5 have been carried out using IR, 1D and 2D NMR spectral data. The NMR spectral data indicate that the N-acyl-2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonanes 3–5 prefer to exist in twin-chair conformation with partial flattening at amide nitrogen end. In order to avoid A1,3-strain with coplanar acyl groups, the phenyl groups at the amide nitrogen end are forced to occupy axial orientation. X-ray crystal structure of the N-dichloroacetyl-2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonane 4 also supports the twin-chair conformation in the solid state. Furthermore, the antibacterial activity for the compounds 2–5 has been carried out.

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