Structural study of 3-azabicyclo[3.3.1]nonane derivatives functionalized at 1 and/or 9-positions by molecular mechanics calculations and NMR spectroscopy

Spectroscopic, Structural, and Computational Characterization of Three Bispidinone Derivatives, as Ligands for Enantioselective Metal Catalyzed Reactions

Three chiral derivatives of the alkaloid sparteine (bispidines), characterized by the 3,7-diazabicyclo[3.3.1]nonane moiety, were designed as efficient ligands in a number of enantioselective reactions due to their metal coordination properties. A full evaluation of the 3D properties of the compounds was carried out, as the geometrical features of the bicyclic framework are strictly related to the efficiency of the ligands in the asymmetric catalysis. The selected molecules have different molecular complexity for investigating the effects of different chiral groups on the bicycle conformation. We report here a thorough analysis of their molecular arrangement, by NMR spectroscopy, single crystal X-ray crystallography, and computational techniques, which put in evidence their conformational preferences and the parameters needed for the design of more efficient ligands in asymmetric synthetic routes. The results confirmed the high molecular flexibility of the compounds, and indicated how to achieve a control of the chair-chair/boat-chair conformational ratio, by adjusting the relative size of the substituents on the piperidine nitrogens.

2,4,6,8-Tetra-kis(4-bromo-phen-yl)-3,7-diaza-bicyclo-[3.3.1]nonan-9-one

In the title compound, C₃₁H₂₄Br₄N₂O, one of the bromo­phenyl rings is disordered over two orientations with occupancies of 0.69 (2) and 0.31 (2). The bicyclo­[3.3.1]nonane ring system adopts a chair–boat conformation. In the crystal structure, mol­ecules are linked into chains along the c axis by inter­molecular C—H⋯O and N—H⋯O hydrogen bonds. Further stabilization is provided by C—H⋯π inter­actions.

Synthesis and Biological Evaluation of a New Family of Constrained Azabicyclic Homocholine Analogues

A family of constrained acylated homocholine analogues have been synthesized, based on the azabicyclic ring scaffold derived from a double-Mannich annulation of cyclic ketones. The short synthetic route allows generation of structural diversity including, variation in the carbocyclic ring size, bridgehead substitution, nitrogen substitution and the ester sidechain. Biological assays on selected analogues demonstrate these compounds are nicotinic acetylcholine receptor (nAChR) antagonists. Several analogues also bind to other neuronal transporter and receptor targets.

1H and 13C NMR spectra of C-6 and C-9 substituted 3-azabicyclco[3.3.1]nonanes

The 1H and 13C NMR data for 3-azabicyclo[3.3.1]nonanes with OH and OMe substituents at C-6 and C-9 were measured using 1D (DEPT) and 2D (COSY, HSQC, HMBC, NOESY) experiments. Comparison of this NMR data illustrates the effects of stereochemistry and substitution at these positions.

1H and 13C NMR spectra of methylmaleimido- and methylsuccinimidoanthranilate esters of 1-hydroxymethyl-6-methoxy-3-azabicyclo[3.3.1]nonanes

The 1H and 13C NMR data for 3-azabicyclo[3.3.1]nonanes having C-1 methylsuccinimidoanthranilate esters and C-6 methyl ethers were measured and assigned using 1D (DEPT) and 2D (COSY, HSQC, HMBC, NOESY) experiments. Comparison of this with previously published data illustrates the effects of stereochemistry and substitution on the basic heterocyclic framework.

1H and 13C NMR data for C-6 substituted 3-azabicyclo[3.3.1]nonane-1-carboxylates

The 1H and 13C NMR spectra of 3-azabicyclo[3.3.1]nonanes with various oxygenated substituents at C-6 were assigned using 1D (DEPT) and 2D (COSY, HSQC, HMBC, NOESY) experiments. Close examination of this NMR data details the effects of substitution and stereochemistry at C-6 in these compounds.