Synthesis,structural, and biochemical study of a series of methyl 2,6-diaryl-1-methyl-4-oxopiperidine-3,5-dicarboxylates and a series of methyl 2,4-diaryl-3,7-dimethyl-9-oxo-3,7-diazabicyclo[3.3.1]nonane-1,5-dicarboxylates

A series of methyl-2,6-diaryl-1-methyl-4-oxopiperidine-3,5-dicarboxylates Ia-c and 2,4-diaryl-3,7-dimethyl-1,5-dimethoxycarbonyl-9-bispidinones IIa-c have been synthesized and studied by ir, ¹H and ¹³C nmr spectroscopy and the crystal structure of methyl 2,4-diphenyl-3,7-dimethyl-9-oxo-3,7-diazabicyclo3,3.1]nonane-1,5-dicarboxylate (IIa) has been determined by X-ray diffraction. The enolic form of compound Ia (I'a) was also studied.