engleski

Fragmentation of diamide derivatives of 3,4- ethylenedioxythiophene

The sequential product ion (MSn) fragmentation of four symmetric diamide derivatives of 3, 4-ethylenedioxythiophene were characterized using ion trap mass spectrometry with electrospray ionization and their fragmentation patterns were studied. The experimental data consists of mass spectra obtained by tandem mass spectrometry, and calculations were obtained by M06-2X/6-31G (d, p) method. Investigated compounds represent building blocks in synthesis of compounds used in different area of chemistry and industry such as in medicinal chemistry, as potential anticancer and anticonvulsant agents, in organic chemistry as linkers for solid-phase synthesis, in synthesis of variety of materials in polymer chemistry. We present herein the investigation of fragmentation pathway of protonated diamide derivatives of 3, 4-ethylenedioxythiophene that involves the identification of fragments, influence of proton transfer on direction of fragmentation and mechanisms of reactions by which fragmentation process occurs. Data obtained from product ion spectra of these protonated compounds and DFT calculations indicate that the fragmentation process takes place via the four main reactions: amido-iminol proton transfer, reverse cycloaddition, cleavage of amide bond, and isocyanic acid elimination. The 3, 4- ethylenedioxythiophene-2, 5-dicarboxamide was observed as intermediate in the fragmentation of its alkyl derivatives. To our knowledge, this work brings the first correct description of the mechanism of elimination of isocyanic acid.

3, 4-ethylenedioxythiophene ; tandem mass spectrometry ; amide-iminol tautomerization ; DFT ; electrospray ionization

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