Substituent Effects on NMR Spectroscopy of 2,2-Dimethylchroman-4-one Derivatives: Experimental and Theoretical Studies
Daniela Iguchi,
Davide Ravelli,
Rosa Erra-Balsells,
Sergio M. Bonesi
Affiliations
Daniela Iguchi
CIHIDECAR-CONICET–Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, 3er Piso, Pabellón 2, Ciudad Universitaria, University of Buenos Aires, CP 1428 Buenos Aires, Argentina
Davide Ravelli
PhotoGreen Lab, Department of Chemistry, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy
Rosa Erra-Balsells
CIHIDECAR-CONICET–Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, 3er Piso, Pabellón 2, Ciudad Universitaria, University of Buenos Aires, CP 1428 Buenos Aires, Argentina
Sergio M. Bonesi
CIHIDECAR-CONICET–Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, 3er Piso, Pabellón 2, Ciudad Universitaria, University of Buenos Aires, CP 1428 Buenos Aires, Argentina
The attribution of 1H and 13C NMR signals of a library of 5-, 6- and 7-substituted 2,2-dimethylchroman-4-one derivatives is reported. Substituent effects were interpreted in terms of the Hammett equation, showing a good correlation for carbons para- to the substituent group, not for the meta- ones. Similarly, the Lynch correlation shows the additivity of the substituent chemical shifts in the case of both H and C nuclei, again with the exception of the carbons in the meta- position. Density Functional Theory (DFT)-predicted 1H and 13C chemical shifts correspond closely with experimentally observed values, with some exceptions for C NMR data; however, the correlation is valid only for the aromatic moiety and cannot be extended to the heterocyclic ring of the chroman-4-one scaffold.
