Relative and absolute configurations of dissolved molecules by NMR-spectroscopy in orienting media

点击翻译按钮获取中文摘要

The aim of this research unit (DFG-Forschergruppe) is the development of a generally applicable and versatile method for the computer-assisted NMR-spectroscopic determination of the relative and absolute configuration of natural products and other organic compounds based on anisotropic NMR-parameters (residual dipolar couplings, RDCs and residual chemical shift anisotropy, RCSA) and the development and application of achiral and chiral orienting media for the relative and absolute configuration, respectively. Since many years parameters like the NOE or the 3J scalar coupling constants have been applied for the conformational analysis of dissolved molecules being biopolymers with defined stereogenic centers in most cases. Due to the lacking parametrization of J-couplings for arbitray compounds, the application of additional structural restraints without this limitation, such as RDC's, is an urgent necessity. Moreover, unlike the NOE/J-coupling based structural elucidation, RDC's are not sensitive to breaks in the scalar or NOE connectivities. This is of special importance in the context of configurational assignments of unknown stereogenic units, particularly if they are far away from each other. To achieve this goal and to meet the need for multiple-alignment data sets, new alignment media (achiral and chiral) as well as new methods for the measurement, interpretation and prediction of RDC's have to be developed. In the following, the progress of the research unit with respect to these goals will be described briefly. After this survey the future research directions will be discussed. Results are described briefly in section 2 and in the individual proposals in their native context.