Synthesis and properties of bridged nitrogen heterocycles
thesisposted on 15.12.2014, 10:35 by Waleed Alkhuraiji
The synthesis of derivatives of the parent 7-azabicyclo[2.2.1]heptyl system was achieved. The synthesis of the novel 1-methyl-7-azabicyclo[2.2.1]hepta-2,5-diene was accomplished. The carbonyl group at position C2 of the 7-azabicyclo[2.2.1]heptyl system was synthesized. The work was extended to include the synthesis of derivatives of the 1,4-dimethyl-7-azabicyclo[2.2.1]heptyl system. Investigation of the synthesis of epibatidine was not successful.;The work was extended to include a wide range of urethanes and amines of 7-azabicyclo[2.2.1]heptyl system where no 15N NMR studies had been reported. The 15N NMR spectra were recorded, in all cases, at natural abundance. The 15N signals of a variety of azabicyclic systems containing the 7-azabicyclo[2.2.1]heptyl skeleton were observed downfield of the more shielded examples reported for several classes of monocyclic and acyclic urethane and amine. The effect of the unsaturation and the substituted carbonyl at position C2 on the 15N chemical shifts was addressed. 14N NMR spectra were measured in some cases where the 15N chemical shifts were difficult to obtain.;X-Ray crystallographic studies showed that urethanes of the bicyclic 7-azabicyclo[2.2.1]heptane are nitrogen-pyramidal. The CNC bond angles, theta angles and alpha angles for 7-azabicyclic urethane derivatives were measured. The CNC bond angles, theta angles and alpha angles for 7-azabicyclic urethane derivatives were calculated for the parent urethanes where x-ray data could not be obtained. Increased planarity at nitrogen correlated with upfield 15N NMR shifts. The CNC bond angles were calculated for the parent amines and the 2-keto-derivative. The calculated CNC bond angles correlated well with the nitrogen NMR shifts. The more downfield nitrogen shift is associated with the small CNC bond angle.