An efficient green protocol for the synthesis of 2-aryl substituted benzothiazoles

Abstract

Cyclocondensation of 2-aminothiophenol and various aryl/heteryl aldehydes was carried in polyethylene glycol-400 as a catalyst and reaction medium at room temperature to obtain 2-aryl substituted benzothiazoles with excellent yields.

Iron nanotube-silica composite (ZVI-S-PCAT modified silica composite) preparation, characterization and application as a recyclable catalytic system for 5-membered ring organic transformations

“…Benzothiazoles have been used as tracing agents for β-amyloid in 5 Alzheimers', invitro activities against human colon, breast and renal cell-lines [39], an iminocoumarin based zinc sensor and as a bioluminogenic substrate. Previous work has included synthesis using microwave conditions having longer time [40], CuCl as catalyst [41], glycerol [36], PEG-400 [42], TsOH [43], nano acid catalysts [44]. mL ethanol and the round bottom flask is fitted to a condenser.…”

“…38 Benzothiazoles have been used as tracing agents for β-amyloid in Alzheimers', in vitro drugs against human colon, breast and renal cell-lines, 39 iminocoumarin based zinc sensors and bioluminogenic substrates. Previous work has included synthesis using microwave conditions with longer time, 40 and using CuCl, 41 glycerol, 36 PEG-400, 42 TsOH, 43 and nanoacid catalysts. 44 To synthesize substituted benzothiazoles, a similar trend of comparison with parallels and optimization of reaction parameters was checked before, as had been performed for the syntheses of imidazole derivatives (described earlier).…”

Pentafluorophenylammonium triflate: A Mild, Efficient and Reusable Catalyst for the Synthesis of 2-Arylbenzothiazole and 2-Arylbenzothiazoline Derivatives in a Green Chemical Approach

“…19 Some catalyst such as CBr 4 , tin-modified monoammonium phosphate fertilizer, acacia concinna bio-catalyst and riboflavin catalyst were applied to develop benzothiazole derivatives in recent years. 20 However, most procedures have some of disadvantages that are hazardous, carcinogenic solvents like chloroform, 21 DMSO, 22 MeCN, 23 dioxane 24 were applied, expensive and toxic catalyst 25 were used, recyclability of the catalyst was noticeable in a few papers 26 and in most papers multistep reaction and complex purification technique were accomodated 27 .…”

Palladium-Catalyzed Synthesis of 2-Aminobenzothiazoles through Tandem Reaction

“…There are mainly two traditional approaches to prepare the 2-substituted benzothiazole ring system. One of which is a condensation reaction of 2-aminothiophenols with aldehydes or carboxylic acid derivatives under strongly acidic conditions, [8][9][10][11][12][13][14][15][16][17][18][19] and the second approach is through cyclization of thiobenzanilides. [20][21][22][23][24][25][26][27] Other procedures such as cyclization of N-(2-halo)arylthioureas (halogen=Br, I) or direct intramolecular C-S bond formation through C-H functionalization of N-arylthioureas catalyzed by transition metals, have enriched the scope of available preparation methods.…”

“…For example, triethylamine (NEt 3 ), NaH, CH 3 ONa, Cs 2 CO 3 , NaOH, and K 2 CO 3 (entries 9-14) were tested and t-BuOK was found to be the most suitable base to promote the reaction. Several other solvents were also tested in this reaction, and all proved less efficient (entries [15][16][17][18][19]. Among the solvents and reaction temperatures examined (entries 20-23), DMSO proved to be the most suitable solvent and the reaction was optimal at 100 °C.…”