title: Spectroscopic, Structural, and Computational Characterization of Three Bispidinone Derivatives, as Ligands for Enantioselective Metal Catalyzed Reactions.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Milan, Milano, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Castellano
authors.affiliation: Department of Chemistry, Materials and Chemical Engineering (CMIC) 'Giulio Natta,' Politecnico di Milano, Milano,, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Sacchetti
authors.affiliation: Department of Pharmaceutical Sciences (DISFARM), University of Milan, Milano, Italy.
authors.forename: Fiorella
authors.initials: F
authors.lastname: Meneghetti
mesh_terms: D001372:Aza Compounds / Q000737:chemistry*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008670:Metals / Q000737:chemistry*; D008968:Molecular Conformation; D010880:Piperidines / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D001372:Aza Compounds; D019086:Bridged Bicyclo Compounds, Heterocyclic; D008024:Ligands; D008670:Metals; D010880:Piperidines; C000609712:bispidinone; C011758:3,7-diazabicyclo(3.3.1)nonane
keywords: asymmetric catalysis; chiral bispidines; conformation analysis; metal coordination