Nuclear magnetic resonance and molecular orbital study of some cocaine analogues
1H NMR spectra of (-)-cocaine and some of its derivatives (α-CPT, β- CPT, nor-β-CIT, cocaine-HCl and ecgonine-HCl) were analysed and the spectral parameters were used for conformational analysis of the compounds in conjunction with theoretical HF/6-31G*, MMP2, AM1 and molecular dynamics calculations. Comparison of the experimental and theoretical data reveals that the compounds are predominantly in a rigid chair conformation, which is rather similar for all compounds. No large differences were found in the dynamical behaviour of the molecules. The performance of the Haasnoot and Altona equations is discussed.