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Theoretical prediction and assignment of vicinal 1 H– 1 H coupling constants of diastereomeric 3‐alkoxy‐6,7‐epoxy‐2‐oxabicyclo[3.3.0]octanes
Author(s) -
Aav Riina,
Pehk Tõnis,
Tamp Sven,
Tamm Toomas,
Kudrjašova Marina,
Parve Omar,
Lopp Margus
Publication year - 2011
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.2712
Subject(s) - vicinal , chemistry , coupling constant , diastereomer , chemical shift , spin (aerodynamics) , computational chemistry , alkoxy group , quantum chemistry , coupling (piping) , spins , molecule , molecular physics , stereochemistry , quantum mechanics , supramolecular chemistry , thermodynamics , organic chemistry , physics , condensed matter physics , mechanical engineering , alkyl , engineering
Spin–spin coupling constants between nuclei in NMR spectroscopy reflect their spatial arrangement. A number of calculation methods, applying different levels of theory, have been developed to support the stereochemical assignment of novel compounds. Nevertheless, revisions of the assignment of structures in the literature are not rare. In the present work, the reliability of the calculation methods amenable for a theoretical prediction of spin–spin coupling constants of vicinal protons to support correct stereochemical assignment of substitution at five‐membered rings of 3‐alkoxy‐6,7‐epoxy‐2‐oxabicyclo[3.3.0]octanes was studied. Experimental 3 J (H,H) coupling constants were compared with the coupling constants calculated for all possible diastereomers. The fully quantum chemical approach provided theoretical 3 J (H,H) coupling constants with an absolute deviation of no more than 1.1 Hz for 91% of the experimentally studied coupled spins, whereas the methods without quantum chemical geometry optimization resulted in completely unreliable predictions. Consequently, for a reliable stereochemical assignment of small and medium size molecules, the protocol for calculating the coupling constants based on the results of the quantum chemical geometry optimization is recommended. Copyright © 2011 John Wiley & Sons, Ltd.