Studies of Dihydropyridines by X-Ray Diffraction and Solid State 13C NMR
2014
Morales-Ríos, Martha S. | Martínez-Richa, Antonio | Hernández-Gallegos, Zurisaddai | Hernández-Barragán, Angelina | Vera-Graziano, Ricardo | Joseph-Nathan, Pedro
Fourteen dimethyl 4-aryl-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylates (DHPs) were evaluated by means of single crystal X-ray diffraction in order to investigate the effects of the structure in the crystals on the solid state ¹³C NMR chemical shifts. These include the analysis of three DHPs containing two molecules per asymmetric unit. The chiral rotamer unit generated by the s-cis/s-trans orientation of the carbonyl groups, as well as by rotation of the 4-phenyl ring out of the bisecting plane containing the N1, C4, C7 atoms, resulted in a significant magnetic non-equivalence for the C2-CH₃/C6-CH₃ and the COOCH₃ pairs of signals. The solid state ¹³C NMR data reveal that the substitution pattern of the phenyl ring has a marked effect on the extent to which the signals of the carbonyl carbon atoms and those of C-2/C-6 peaks are split.
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