title: The use of residual dipolar coupling for conformational analysis of structurally related natural products.
abstract: Determining the conformational preferences of molecules in solution remains a considerable challenge. Recently, the use of residual dipolar coupling (RDC) analysis has emerged as a key method to address this. Whilst to date the majority of the applications have focused on biomolecules including proteins and DNA, the use of RDCs for studying small molecules is gaining popularity. Having said that, the method continues to develop, and here, we describe an early case study of the quantification of conformer populations in small molecules using RDC analysis. Having been inspired to study conformational preferences by unexpected differences in the NMR spectra and the reactivity of related natural products, we showed that the use of more established techniques was unsatisfactory in explaining the experimental observations. The use of RDCs provided an improved understanding that, following use of methods to quantify conformer populations using RDCs, culminated in a rationalisation of the contrasting diastereoselectivities observed in a ketone reduction reaction.
authors: School of Chemistry and Biomedical Sciences Research Complex, University of St Andrews and EaStCHEM, North Haugh, St Andrews, KY16 9ST, UK.
authors: Christopher S
authors: CS
authors: Lancefield
authors: School of Chemistry and Biomedical Sciences Research Complex, University of St Andrews and EaStCHEM, North Haugh, St Andrews, KY16 9ST, UK.
authors: Alexandra M Z
authors: AM
authors: Slawin
authors: School of Chemistry and Biomedical Sciences Research Complex, University of St Andrews and EaStCHEM, North Haugh, St Andrews, KY16 9ST, UK.
authors: Nicholas J
authors: NJ
authors: Westwood
authors: School of Chemistry and Biomedical Sciences Research Complex, University of St Andrews and EaStCHEM, North Haugh, St Andrews, KY16 9ST, UK.
authors: Tomas
authors: T
authors: Lebl
mesh_terms: D001688:Biological Products / Q000138:chemical synthesis / Q000737:chemistry*; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D046948:Secologanin Tryptamine Alkaloids / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D001688:Biological Products; D046948:Secologanin Tryptamine Alkaloids; C545603:melohenine B
keywords: 13C; 1H; NMR; conformational analysis; melohenine; natural products; residual dipolar couplings; solution conformations