Synthesis, structural and conformational study of some amides derived from 3-methyl-3-azabicyclo[3.2.1]octan-8α(β)-amines

✍ Scribed by I. Iriepa; J. Bellanato; E. Gálvez; A.I. Madrid

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 151 KB
• Volume: 886
• Category: Article
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2007.10.029

✦ Synopsis

Some amides (1a-7a and 1b-7b) derived from 3-methyl-3-azabicyclo[3.2.1]octan-8a(b)-amines were synthesized and studied by IR, 1 H and 13 C NMR spectroscopies. The assignment of all carbon and protons resonances was achieved through the application of one dimensional selective NOE and two dimensional NMR techniques: homonuclear NOESY and heteronuclear 1 H-13 C gHSQC correlated spectroscopies. Total correlation spectroscopy (TOCSY) experiments were also carried out.

In CDCl 3 solution, at room temperature, all compounds adopt a chair-envelope conformation with the N-CH 3 group in equatorial disposition. In the a-epimers the piperidine ring is puckered at C8 to relieve the interactions between the amido group and the H6(7)x protons.

a-and b-Epimers show a preferred trans disposition for the NH-CO group and free rotation of the NH-CO-R group around the C8-NH bond. Finally, NMR and IR data reveal that compounds 7a and 7b adopt in CDCl 3 solution a preferred s-cis conformation