Structural and spectroscopic characterization of oxo-sparteines

The equilibrium structures of the 11 possible oxo-derivatives of sparteine were investigated with the density functional theory, using the B3LYP functional, and the electronic structure of the oxo-sparteines was examined by measuring and calculating relevant parameters of their NMR and photoelectron spectra

A combined spectroscopic and theoretical study of oxo- and thiono-sparteines

Density functional theory calculations with the B3LYP hybrid functional have been performed to determine the equilibrium structures of a representative series of thiono-, oxo,thiono-, dioxo-, and dithiono-derivatives of sparteine. All these molecules except 2,13-dioxo-sparteine adopt one most stable conformation or exhibit a marked preference for one of the two lowest-energy conformations of the parent sparteine (with each functionalized ring distorted as a sofa or half-chair). 2,13-Dioxo-sparteine is instead predicted to exist as a nearly 1:1 mixture of \u2018\u2018ring C chair\u2019\u2019 and \u2018\u2018ring C boat\u2019\u2019 conformers in solution. The theoretical structural models are consistent with the available X-ray experimental results. The electronic structure of these bis-quinolizidine alkaloids has been studied by measuring and calculating important features of their NMR and photoelectron spectr