Abstract
Floating chirality restrained distance geometry (fc-rDG) calculations are used to directly evolve structures from NMR data such as NOE-derived intramolecular distances or anisotropic residual dipolar couplings (RDCs). In contrast to evaluating pre-calculated structures against NMR restraints, multiple configurations (diastereomers) and conformations are generated automatically within the experimental limits. In this report, we show that the “unphysical” rDG pseudo energies defined from NMR violations bear statistical significance, which allows assigning probabilities to configurational assignments made that are fully compatible with the method of Bayesian inference. These “diastereomeric differentiabilities” then even become almost independent of the actual values of the force constants used to model the restraints originating from NOE or RDC data.
Highlights
Floating Chirality Distance GeometryThe determination of the relative or even absolute configuration of natural products has a long-standing history in organic chemistry
Parameters measured in isotropic solutions, auxiliary information can be obtained from residual dipolar or quadrupolar couplings (RDCs [24,25,26,27,28] and RQCs [24,29,30,31]), as well as residual chemical shift anisotropies (RCSAs [3,6,32,33,34,35,36,37,38]) measured in anisotropic environments of single or multi-alignment media [24,39,40,41,42,43,44,45,46]. These anisotropic parameters contain additional valuable angle information between even distant molecular fragments, which turn out to be very helpful with regard to the exact molecular geometry
The elucidation of molecular configurations and/or conformations from NMR data can be divided into two major categories as either “static” or “dynamic” approaches
Summary
Floating Chirality Distance GeometryThe determination of the relative or even absolute configuration of natural products has a long-standing history in organic chemistry. Given the known constitution of compounds, NMR-derived parameters such as scalar couplings and cross-relaxation (NOE or ROE)-derived interproton distances [22,23] add valuable information to the relative configuration and conformation of compounds In addition to these traditional NMR parameters measured in isotropic solutions, auxiliary information can be obtained from residual dipolar or quadrupolar couplings (RDCs [24,25,26,27,28] and RQCs [24,29,30,31]), as well as residual chemical shift anisotropies (RCSAs [3,6,32,33,34,35,36,37,38]) measured in anisotropic environments of single or multi-alignment media [24,39,40,41,42,43,44,45,46]. In the “static” approximation, pre-calculated molecular models are tested against experimental
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