Utilization of the selective pulse INEPT NMR experiment (INAPT) for the facile distinction of quaternary carbons attached to a trisubstituted alkene
✍ Scribed by Michael A. Bernstein
- Publisher
- John Wiley and Sons
- Year
- 1989
- Tongue
- English
- Weight
- 396 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
The INEPT experiment which uses selective 'H pulses (INAPT) was used to assign quaternary carbon NMR signals in trisubstituted alkenes. Given that '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 pharmaceuticals, cyclobenzaprine and amitriptyline, 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 heteronuclear J-resolved and heteronuclear nuclear Overhauser effect experiments.