Theoretical and experimental 1H, 13C and 15N NMR studies of N-alkylation of substituted tetrazolo[1,5-a]pyridines

Experimental and Computational Studies on N-alkylation Reaction of N-Benzoyl 5-(Aminomethyl)Tetrazole

The N-alkylation reaction of N-benzoyl 5-(aminomethyl)tetrazole (5-AMT) with benzyl bromide was carried out in the presence of K2CO3 as a base. Two separable regioisomers were obtained, thus their purification led to determine the proportion of each of them, and their structures were attributed essentially based on 1H and 13C NMR spectroscopy in addition to the elemental analysis and MS data. In order to confirm the results obtained at the synthesis level, a computational study was carried out by application of density functional theory (DFT) using the Becke three-parameter hybrid exchange functional and the Lee-Yang-Parr correlation functional (B3LYP).

Comparison of GIAO and CSGT for calculating (13) C and (15) N nuclear magnetic resonance chemical shifts of substituent neutral 5-aminotetrazole and 5-nitrotetrazole compounds

The comparison of the gauge-including atomic orbital (GIAO) and the continuous set of gauge transformation methods for calculating nuclear magnetic chemical shifts (CSs) mainly at density functional levels of theory are presented. Isotropic (13)  C and (15)  N magnetic CS for 14 compounds of tetrazoles are reported. Compared with establishing a convenient and consistent protocol to be employed for confirming the experimental (13)  C and (15)  N NMR spectra of tetrazole compounds, different combinations of functionals and basis sets were considered. The most reliable results were obtained at GIAO/B3LYP/aug-cc-pVDZ with integral equation formulation for the polarizable continuum model (PCM), which has the smallest root mean square errors and can be used to calculate (13)  C and (15)  N NMR CS with a very high accuracy for tetrazoles. These results show that the accurately calculated (15) N NMR CS of tetrazoles could be used for the evaluation of the intrinsic relationship between structure and explosive properties.