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Assignments of the 1 H and 13 C NMR spectra of pseudo‐symmetric heterocyles using the HMQC‐TOCSY experiment to differentiate overlapping spin systems
Author(s) -
Castle Lyle W.,
Johnston Milton D.,
Camoutsis Charalampos L.,
Castle Raymond N.
Publication year - 1992
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570290722
Subject(s) - chemistry , quinoline , spectral line , proton , nmr spectra database , spin (aerodynamics) , molecule , nuclear magnetic resonance spectroscopy , stereochemistry , carbon 13 nmr , crystallography , organic chemistry , physics , nuclear physics , astronomy , thermodynamics
The 1 H nmr spectra of phenanthro[9′,10′:4,5]thieno[2,3‐ c ]quinoline, benzo[ f ]phenanthro‐[9′,10′:4,5]thieno[2,3‐ c ]quinoline and benzo[ h ]phenanthro[9′,10′:4,5]thieno[2,3‐ c ]quinoline are highly congested. For each compound, all protons abide in an aromatic environment complicated by pseudo‐symmetric regions which result in multiple overlap of the different spin systems these molecules contain. We illustrate here the utility of the HMQC‐TOCSY experiment to identify spin systems when the proton spectrum is highly congested. To complete the assignment of the 1 H and 13 C nmr spectra of each compound the HMBC experiment is used to assign the quaternary carbons.