CONFORMATIONAL-ANALYSIS .38. 8-TERT-BUTYL-TRANS-DECAHYDROQUINOLINES - C-13 AND H-1 NUCLEAR MAGNETIC-RESONANCE AND INFRARED-SPECTRA - N-H CONFORMATIONAL EQUILIBRIUM

Synthesis and spectra (13C and 1H NMR, IR) of the two 8-tert-butyl-frans-decahydroquinolines (4 and 5) and of their N-methyl derivatives are reported. Comparison with the spectra of trans-decahydroquinoline (1) and of the two 8-methyl-trans-decahydroquinolines (2 and 3) suggests that the proton on N is preferentially equatorial in 1, 2, 3, and 5, but is forced into a predominantly axial position by the (equatorial) 8-tert-butyl group in 4. The chemical shifts of the protons α to nitrogen (H2e, H2a) are not significantly influenced by the relative positions of the proton and electron pair on nitrogen. © 1979, American Chemical Society. All rights reserved.