INSIGHT INTO THE CONFORMATIONAL SPACE OF N-BENZYL-N-(FURAN-2-YLMETHYL)ACETAMIDE BY NMR SPECTROSCOPY AND DFT CALCULATIONS

ROMANELLI, GUSTAVO; CASTAÑO, JOVANNY; LOAIZA, ALIX; TOBÓN, YENY; MONTAÑA, JEISSON; WAELE, ISABELLE

QUíMICA NOVA

SOC BRASILEIRA QUIMICA

Año: 2021

0100-4042

In this study, the conformational behavior of N-benzyl-N-(furan-2-ylmethyl) acetamide in chloroform was addressed by usinga combined experimental/theoretical strategy using NMR spectroscopy and quantum chemical calculations. The 1H and 13Cone-dimensional NMR spectra, as well as the two-dimensional HSQC-DEPT and HMBC-DEPT NMR spectra, evinced the presenceof a hindered cis(E)-trans(Z) rotational equilibrium in solution. DFT calculations were performed at different theoretical levels usingthe polarizable continuum model (PCM) and predicted nine (four Z and five E structures) stable conformations. The interconversiondynamics among the different confirmations were established in terms of four different rotational equilibria in CDCl3. The chemicalshifts in the 1H and 13C NMR spectra of the compound are similar to the values calculated for the two most abundant conformationalequilibria at room temperature, one caused by two Z rotamers and the other by two E rotamers. The compound was also characterizedfor the first time by FTIR, Raman spectroscopy, and GC/MS spectrometry. Additionally, several acylation methodologies forsynthesizing the title compound from N-benzyl-1-(furan-2-yl)methanamine were tested which resulted in high yields (> 90%) undervery convenient conditions (10 min, at room temperature).