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Application of the conformational transmission effect for the assignment of diastereotopic proton resonances
Author(s) -
van Genderen Marcel H. P.,
Buck Henk M.
Publication year - 1987
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.1260251009
Subject(s) - chemistry , proton , stereochemistry , proton nmr , nuclear magnetic resonance spectroscopy , crystallography , quantum mechanics , physics
A new method is presented for the assignment of the NMR resonances of the diastereotopic protons in tetrahydrofur‐furyl and pyrrolidinylmethyl groups, based on the conformational transmission effect This effect describes the conformational changes produced by an increase of coordination from four to five of a phosphorus, silicon or germanium atom attached to the tetrahydrofurfuryl or pyrrolidinylmethyl moieties. The 1 H NMR conformational analysis of these cyclic four‐ and five‐coordinated compounds yields two possible results, based on two assignments of the diastereotopic proton resonances. Comparison with the conformations of the analogous four‐ and five‐coordinated systems with acyclic 2‐methoxyethyl and dimethylaminoethyl groups (which lack diastereotopic protons) directly shows which assignment is correct, since a similar conformational transmission occurs in both the cyclic and the acyclic compounds.