Synthesis and Characterization of the Structure of Diethyl [(4-{(1H-Benzo[d]Imidazol-1-yl)Methyl}-1H-1,2,3-Triazol-1-yl)(Benzamido)Methyl]Phosphonate Using 1D and 2D NMR Experiments

The biheterocyclic derivative of the phosphonic glycine analogue is prepared selectively by reaction between the α-azidoamino diethyl methylphosphonate and the 1-(prop-2-yn-1-yl)-1H-benzo[d]imidazole. The dipolar -1,3 cycloaddition reaction using Click Chemistry was carried out in a solvent water/ethanol mixture in a ratio of 1:1. Copper sulphate pentahydrate and sodium ascorbate are used in the reaction in catalytic amounts. The compound [diethyl [{4-[(1H-benzo[d]imidazol-1-yl)methyl]-1H-1,2,3-triazol-1-yl}(benzamido) methyl] phosphonate was isolated pure as a white powder, after chromatography on a silica gel column (ethyl acetate/hexane acetate: 1/1). The yield of pure product is 90%, after recrystallization in an ether/hexane mixture. The structure of the -1,4 isomer is attributed to the compound obtained by means of 1D and 2D NMR and based on data from the literature concerning the cycloaddition reaction via Click Chemistry. Two-dimensional NMR spectroscopy played a major role. The analysis of the different correlations between adjacent hydrogens and carbons, and also between hydrogens and distant carbons, confirmed the proposed structure.