Abstract
Electrophilic behaviour of 3-methyl-2-methylthio-1,3,4-thiadiazolium salts: A multimodal theoretical approach
Highlights
2-Amino-1,3,4-thiadiazole systems have received much attention owing to their industrial applications,[1] as well as their wide range of biological activities,[2] and their incorporation into supramolecular entities.[3]
We have recently reported a versatile strategy for the synthesis of highly functionalized 2-oxo, 2-thioxo, 2-imino, or 2methylene-1,3,4-thiadiazolines with a C, N, or S-substituent at the position- 5 (2), as well as the respective cationic or mesoionic counterparts, by reaction of the appropriate O, N- or Cnucleophiles with the corresponding 5-substituted 3-methyl-2-methylthio-1,3,4-thiadiazolium salts 1 (Figure 1).6 2-Thioxo-thiadiazolines were only obtained as S-demethylation products when halide or carboxylate anions were present in the reaction mixture
The evaluation of the stability of all possible reaction products arising from the treatment of 2-methylthiothiadiazolium salts (1) with nucleophiles might afford a valuable criterion to explain the major species obtained in every case, for the limiting situation in which the experiments were carried out under conditions of thermodynamic control
Summary
2-Amino-1,3,4-thiadiazole systems have received much attention owing to their industrial applications,[1] as well as their wide range of biological activities,[2] and their incorporation into supramolecular entities.[3]. The extent of positive charge over the substituent Z is not necessarily proportional to the contribution of the resonant structure bearing it, one can conclude that structure 1III is relevant enough to account for a significant decrease in the aromaticity of 2- substituted thiadiazolium cations 1, in accordance with that suggested by ASE and NICS data.
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