Conformational and configurational studies on 3‐azabicyclo[3.3.1]nonane (3‐abn) derivatives and related systems employing carbon‐13 NMR spectroscopy

Abstract

The 13C nmr spectra of 4 cis‐2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonanes, 11 cis‐2,4‐diaryl‐3‐azabicyclo[3.3.1]‐nonan‐9‐ones, 26 cis‐2,4‐diaryl‐3‐azabicyclo[3.3.1]‐nonan‐9‐ols or acetates thereof, 5 cis‐2,4‐diaryl‐3‐azabi‐cyclo[4.3.1]decan‐10‐ones or ‐10‐ols and 5 cis‐2,4‐diphenyl‐3‐aza‐7‐thiabicyclo[3.3.1]nonan‐9‐ones, ‐9‐ols or 9‐yl acetates have been recorded. Except for the 7‐thia compounds, which appear to exist mainly in the configuration and conformation with the nitrogen‐containing ring in the boat form, these compounds seem to exist overwhelmingly in chair‐chair conformations. The configuration of the 9‐ols and their acetates (syn or anti to the nitrogen‐containing ring) has been deduced from the spectra. In a number of cases, the structures assigned differ from those earlier postulated. Broadening of one set of aryl signals (probably those due to the ortho carbons) in the case of N‐methyl (but not N‐H) compounds without ortho substituents is ascribed to restricted phenyl rotation.

Synthesis, structural, conformational and pharmacological study of esters derived from 3‐methyl‐2,4‐diphenyl‐3‐azabicyclo[3.3.1]nonan‐9α‐ol as potential analgesics

“…In the 13 C NMR spectra, the twin-chair conformation is confirmed by the C2(4) and C6(8) chemical shifts 21 ( Table 7). For a boat conformation, the carbon signals would be shifted to a higher field because of the steric compressing effect due to the eclipsing between H2(4) ax -H1(5) and H6(8) ax -H1 (5) hydrogen atoms.…”

Synthesis of tricyclic analogues of methyllycaconitine using ring closing metathesis to append a B ring to an AE azabicyclic fragment

“…This γ-gauche effect has been extensively studied in 3-azabicyclo [3.3.1]nonane ring systems. [23][24][25][26] The chemical shift of the ring carbons that are syn to the hydroxyl group are shifted upfield when compared to the chemical shift of the nonhydroxyl ring system. Both diastereomers 6 and 7 exhibited similar C-7 shifts consistent with a chair-chair conformation of the azabicyclo[3.3.1]nonane ring system as depicted in Fig.…”

Synthesis, characterization and stereochemistry of N-acyl-r-2,c-4-bis(4-methoxyphenyl)-3-azabicyclo[3.3.1]nonanes

“…The preferred conformations of the N-acyl-2,4-bis(4-methoxyphenyl)-3-azabicyclo[3.3.1]nonanes 3-6 were derived from 1 H and 13 C NMR spectral data in comparison with those of the parent amine 2 [8,9,11] which exist in twin-chair conformation with equatorial orientation of anisyl groups (Fig. 1).…”

“…The synthesis and stereochemistry of 3-azabicyclo[3.3.1]nonan-9-ones have been reported earlier [4][5][6][7][8][9][10]. The conformational http://dx.doi.org/10.1016/j.molstruc.2015.03.052 0022-2860/Ó 2015 Elsevier B.V. All rights reserved.…”