Microwave preparation of triazoles was performed by students from benzyl, acetonyl or phenacyl halides, sodium azide and methyl propiolate in two stages in the presence of Cu(I), resulting in solid 1,4-disubstituted 1<i>H</i>-1,2,3-triazole esters in good yield. The products were partially characterized by melting point, NMR and IR spectroscopy. 2D-NMR analyses were used to confirm the substitution pattern of substituents on the triazole ring. The Sharpless/Meldall, copper-catalyzed method of synthesis is known to give 1,4-disubstituted products, but NMR spectroscopy was used by students to verify the structure of the products. In all, students prepared the triazole, purified it and ran spectra in two or three lab periods. The microwave-assisted syntheses and work-up required one lab period. Purification through recrystallization, if desired, required one period and characterization of the crude product or the dried, recrystallized product required one period. Alternatively, students prepared 1,4,5-trisubstituted triazole diesters via microwave-assisted condensation of dimethyl acetylenedicarboxylate with an organic azide. Characterization of these products did not require 2D-NMR spectroscopy, but <sup>1</sup>H NMR spectroscopy did show differentiation between the two different methyl ester groups at the C-4 and C-5 positions of the triazole. The NMR spectroscopic features of the experiments will be emphasized in the presentation.

One-pot microwave experiments with NMR characterization of synthetic triazole esters

253rd National Meeting (2017)

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