Synthesis, structure and conformational analysis of 2,4-diaryl-3-azabicyclo[3.3.1]nonan-9-one thiosemicarbazones and semicarbazones

A series of thiosemicarbazones and semicarbazones have been synthesized and characterized by one and two dimensional NMR spectroscopy. The possible ring conformations of both the hydrazones are discussed. The chemical shifts and coupling constants suggest that the reported hydrazones adopt twin-chair conformations with equatorial orientation of the aryl substituents. Besides, the proposed conformations are further confirmed by single crystal X-ray diffraction analysis and molecular optimization geometry method.