Síntese, caracterização e derivatização de 1-(2,6-difluorbenzil)-5-metil-1H-1,2,3-triazol-4-il-carbohidrazida

Abstract

This final course assignment describes the experimental studies about the use of 1-(2,6-difluorobenzyl)-5-methyll-1H-1,2,3-triazole-4-il-carbohydrazide in a synthetic development to obtain novel compounds, namely, 1-(2,6-difluorobenzyl)-5-methyl-N'(ferrocenylmethylene)-1H-1,2,3-triazole-4-carbohydrazide (ferrocenyl derivative) and 1-(2,6-difluorobenzyl)-N-(2,5-dimethyl-1H-pyrrol-1-yl)-5-methyl-1H-1,2,3-triazole-4-carboxamide (pirrole derivative). The initial step, i.e, the 1,3-dipolar cycloaddition reaction between 4-methoxy-1,1,1-trichloro-3-penten-2-one and 2,6-difluorobenzyl azide, achieved the 4-trichloroacetyl-1-(2,6-difluorobenzyl)-5-methyl-1H-1,2,3-triazole in 60% yield. As an intermediary step, a haloformic reaction between 4-trichloroacetyl-1-(2,6-difluorobenzyl)-5-methyl-1H-1,2,3-triazole and hydrazine monohydrate resulted in 1-(2,6-difluorobenzyl)-5-methyl-1H-1,2,3-triazol-4-yl-carbohydrazide in 78% yield. At the final reaction steps, a reaction between 1H-1,2,3-triazol-4-yl-carbohydrazide and ferrocene carbaldehyde allowed the synthesis of an imine (base de Sciff), namely 1-(2,6-difluorobenzyl)-5-methyl-N'(ferrocenylmethylene)-1H-1,2,3-triazole-4-carbohydrazide in 50% yield and a [4+1] cyclocondensation reaction of 1H-1,2,3-triazol-4-yl-carbohydrazide with 2,5-hexanodione allowed to isolate 1-(2,6-difluorobenzyl)-N-(2,5-dimethyl-1H-pyrrol-1-yl)-5-methyl-1H-1,2,3-triazole-4-carboxamide in 30% yield. Finally, it was performed the structural characterization of the new compounds obtained by 1H , 13C, NMR spectroscopy techniques, Gas Chromatography coupled to Mass Spectrometry (GC-MS) and DFT calculations for compound N'(ferrocenylmethylene)-1H-1,2,3-triazole-4-carbohydrazide indicating the configuration E(cis), as the most stable for this complex hydrazide.