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Utilization of the selective pulse INEPT NMR experiment (INAPT) for the facile distinction of quaternary carbons attached to a trisubstituted alkene
Author(s) -
Bernstein Michael A.
Publication year - 1989
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.1260270710
Subject(s) - chemistry , heteronuclear molecule , alkene , nuclear overhauser effect , polarization (electrochemistry) , pulse sequence , nuclear magnetic resonance spectroscopy , computational chemistry , stereochemistry , organic chemistry , nuclear magnetic resonance , catalysis , physics
The INEPT experiment which uses selective 1 H pulses (INAPT) was used to assign quaternary carbon NMR signals in trisubstituted alkenes. Given that 3 J(CH) across the double bond is usually larger for the trans than the cis disposed nuclei, experimental conditions may be chosen such that more polarization transfer is effected in the case of the trans nuclei. We applied this approach to two important pharmaceutica Is, cyclobenzaprine and ami‐triptyline, and some structurally related compounds. In each case the INAPT experiment quickly afforded a stereochemical assignment. Assignments were corroborated with the data from two‐dimensional selective hetero‐nuclear J‐resolved and heteronuclear nuclear Overhauser effect experiments.