Monroy-Cárdenas M, Gavín JA, Araya-Maturana R. Assessment of the Long-Range NMR C,H Coupling of a Series of Carbazolequinone Derivatives.
Int J Mol Sci 2023;
24:17450. [PMID:
38139280 PMCID:
PMC10744212 DOI:
10.3390/ijms242417450]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 11/29/2023] [Accepted: 12/01/2023] [Indexed: 12/24/2023] Open
Abstract
Synthesis, the complete 1H- and 13C-NMR assignments, and the long-range C,H coupling constants (nJC,H) of some hydrogen-deficient carbazolequinones, assessed by a J-HMBC experiment, are reported. In these molecules, the protons, used as entry points for assignments, are separated by several bonds with non-protonated atom carbons. Therefore, the use of long-range NMR experiments for the assignment of the spectra is mandatory; we used HSQC and HMBC. On the other hand, the measured heteronuclear (C,H) coupling constants 2J to 5J) allow us to choose the value of the long-range delay used in the HMBC experiment less arbitrarily in order to visualize a desired correlation in the spectrum. The chemical shifts and the coupling constant values can be used as input for assignments in related chemical structures.
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