Gated Decoupling 13C NMR Application to Determine Conformation and Unambiguous Chemical Shift of Arylidene Barbiturates

Design, synthesis, structure, toxicology and in vitro testing of three novel agents for Alzheimer’s disease

“…The complete chemical shi assignments and threedimensional structures of these new compounds were determined using NMR by collecting 1 H, 13 C-APT, gCOSY, ROESY-1D, gHSQC and gHMBC spectra. [12][13][14][15][16][17][18][19][20][21] All the NMR results were conrmed by molecular modeling. The NMR data for compound 5, including the 1 H, 13 C, gHSQC and gHMBC spectra, are shown in Tables 1 and 2.…”

“…NMR is effective for determining three-dimensional structures and assigning chemical shis for new molecules because many different types of spectra can be obtained; 1 H, 13 C, COSY, TOCSY, HSQC, HMBC, NOESY, ROESY and gated decoupling of 13 C are all especially effective methods. [12][13][14][15][16][17][18][19][20][21] This article describes the complete synthesis of three novel compounds and the complete, non-questionable determination of their three-dimensional structures and chemical shi assignments using NMR. The NMR results are conrmed by molecular modeling.…”

Synthesis, Three-Dimensional Structure, Conformation and Correct Chemical Shift Assignment Determination of Pharmaceutical Molecules by NMR and Molecular Modeling

“…In general terms, the gated decoupling of 13 C NMR is very important to determine the chemical shift of all quaternary carbons, a process that have been used to confirm the structure and chemical shift of pharmacological agents. 18 In order to determine the three dimensional structure of molecules, despite the complete chemical shift assignment, it is also necessary the application of NOE. The NOE methods allow the calculation of dipolar coupling, a process that determines which hydrogens are close to other ones and the correlation distance without the participation of bonds.…”

“…To determine the values of n J CH several procedures can be used, such as IPAP-HSQMBC, 16 and SHESSLOC, 17 but the simple and very easy to apply this method is the gated decoupling of 13 C NMR. 18 One example of gated decoupling of 13 C NMR application is on compound 5, which was synthesized as shown in Figure 4.…”