A convenient one-pot synthesis of 2-benzimidazolyl-thioacetophenones and thiazolo[3,2-a]benzimidazoles

Regioselective reaction of imidazole-2-thiols with N-sulfonylphenyldichloroacetaldimines: en route to novel sulfonylamino-substituted imidazo[2,1-b]thiazoles and thiazolo[3,2-a]benzimidazoles

“…The advantages of the method for the preparation of the imidazothiazole and thiazolobenzimidazole derivatives are available starting reagents, catalyst-free one-step procedure, and high selectivity. The known methods 19,[21][22][23][24] have never been used for the preparation of sulfonylaminosubstituted derivatives containing synthetically useful and pharmacophoric sulfonamide groups. It can be argued that the method proposed herein complements the known literature protocols and expands the scope of functionalized imidazothiazoles derivatives which are now available for further investigation of biological activity and other properties.…”

“…19,21 Thiazolobenzimidazoles bearing the imidazo [2,1-b]thiazole fragment were obtained by the reaction of benzimidazole-2-thiol with bromomalononitrile. 11,[22][23][24] We are engaged in elaboration of approaches to the preparation of annulated imidazole derivatives containing synthetically important pharmacophoric sulfonylamino group. [25][26][27][28] It is a common knowledge that the sulfonamide compounds are intensively employed for drug design.…”

Nucleophilic addition of enaminones to the S-S dimer of 2-aminobenzenethiol

“…On the basis of the well established chemistry of enaminones and diaryl disulfides 1,19,20 it is reasonable to assume that compounds 3a-c result from nucleophilic addition of enaminones on the S-S dimer of 2-aminobenzenethiol which acts as an electrophile, followed by cleavage of disulfide bond to form of an α-(2-amino phenyl sulfonyl)enaminone intermediate and 2-amino-benzenethionl anion which the thiolate anion is easily oxidized by oxygen (air) to yield the dimer of 2-aminobenzenethionl. Thus only 0.5 equivalents of dimer 2 is needed.…”

Novel Method for the Synthesis of s-Triazolo[3,4-b][1,3,4]thiadiazines

“…29 The advantages of this method are short reaction time, one-pot reaction, direct use of ketones without the formation of highly toxic and irritating phenacyl bromides, ease of handling, very inexpensive materials and the ease of removal of the reaction waste by neutralization of the liquor with ammonium hydroxide. We believe that this reaction can be considered a clean reaction and environmentally safe.…”

“…Recently, we have reported the synthesis of triazolo [1,3,5]thiadiazines via a double Mannich reaction. 27,28 In the present work we report a facile synthesis of s-triazolo [3,4-b] [1,3,4]thiadiazines, using our method that we previously applied for the synthesis of thiazoloimidazoles 1 and thiazolotriazoles 2 (Figure 1), [29][30][31][32] in short reaction time and good reaction yields.…”