title: Steric and electronic effects on the configurational stability of residual chiral phosphorus-centered three-bladed propellers: tris-aryl phosphane oxides.
abstract: A series of tris-aryl phosphane oxides existing as residual enantiomers or diastereoisomers with substituents on the aryl rings differing in size and electronic properties were synthesized and characterized. Their electronic properties were evaluated on the basis of their electrochemical oxidation and reduction potentials together with those of the corresponding "blade bromides" (i.e., the naphthalene derivatives displaying the same substitution pattern of the tris-naphthyl phosphane oxide blades, with a bromo substituent where the phosphorus atom is located) determined by CV. The residual stereoisomeric phosphane oxides were isolated in a stereochemically pure state and were found to be highly configurationally stable at room temperature (stereoisomerization barriers of about 27 kcal mol(-1)). The chiroptical properties of the residual stereoisomers and the assignments of absolute configuration are discussed. The configurational stability of residual tris-aryl phosphane oxides was found to be scarcely influenced by the electronic properties of the substituents present on the aromatic rings constituting the blades, while steric effects play the most relevant role. Detailed theoretical calculations are in agreement with the experimental results and also contribute to a rational interpretation of the stereodynamics of these systems.
authors.affiliation: Dipartimento di Scienza e Alta Tecnologia, Università dell'Insubria via Valleggio 11, 22100 Como, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Benincori
authors.forename: Valentina
authors.initials: V
authors.lastname: Bonometti
authors.forename: Roberto
authors.initials: R
authors.lastname: Cirilli
authors.forename: Patrizia R
authors.initials: PR
authors.lastname: Mussini
authors.forename: Andrea
authors.initials: A
authors.lastname: Marchesi
authors.forename: Marco
authors.initials: M
authors.lastname: Pierini
authors.forename: Tullio
authors.initials: T
authors.lastname: Pilati
authors.forename: Simona
authors.initials: S
authors.lastname: Rizzo
authors.forename: Francesco
authors.initials: F
authors.lastname: Sannicolò
mesh_terms: D001555:Benzene Derivatives / Q000737:chemistry; D004355:Drug Stability; D004563:Electrochemistry; D008958:Models, Molecular; D008968:Molecular Conformation; D009943:Organophosphorus Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D001555:Benzene Derivatives; D009943:Organophosphorus Compounds; D010087:Oxides; D010720:Phosphines; C044646:phosphine