Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction

1Citations
Citations of this article
8Readers
Mendeley users who have this article in their library.

Abstract

This paper reports the synthesis of a series of piperidones 1–8 by the Mannich reaction and analysis of their structures and confor-mations in solution by NMR and mass spectrometry. The six-membered rings in 2,4,6,8-tetraphenyl-3,7-diazabicyclo[3.3.1]nonan-9-ones, compounds 1 and 2, adopt a chair–boat conformation, while those in 2,4-diphenyl-3-azabicyclo[3.3.1]nonan-9-ones, com-pounds 3–8, adopt a chair–chair conformation because of stereoelectronic effects. These stereoelectronic effects were analyzed by the 1 J C–H coupling constants, which were measured in the 13 C satellites of the 1 H NMR spectra obtained with the hetero-dqf pulse sequence. In the solid state, these stereoelectronic effects were investigated by measurement of X-ray diffraction data, the molec-ular geometry (torsional bond angles and bond distances), and inter-and intramolecular interactions, and by natural bond orbital analysis, which was performed using density functional theory at the ωB97XD/6311++G(d,p) level. We found that one of the main factors influencing the conformational stability of 3–8 is the interaction between the lone-pair electrons of nitrogen and the anti-bonding sigma orbital of C(7)–H eq (n N →σ* C–H(7)eq), a type of hyperconjugative interaction.

Cite

CITATION STYLE

APA

Garcias-Morales, C., Ortegón-Reyna, D., & Ariza-Castolo, A. (2015). Investigation of the role of stereoelectronic effects in the conformation of piperidones by NMR spectroscopy and X-ray diffraction. Beilstein Journal of Organic Chemistry, 11, 1973–1984. https://doi.org/10.3762/bjoc.11.213

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free