Synthesis of 2-arylbenzimidazoles under mild conditions catalyzed by a heteropolyacid-containing task-specific ionic liquid and catalyst investigation by electrospray (tandem) mass spectrometry

Abstract

A task-specific ionic liquid constituted by a Bronsted acid (1-(3-sulfopropyl)-3-methyl-imidazolium hydrogen sulfate), namely MSI, and by [PW12O40]3−, namely PW, was used for the condensation reaction in the synthesis of 2-arylbenzimidazoles.

Seleno/Thio-functionalized ipso-Annulation of N-Propiolyl-2-arylbenzimidazole to Construct Azaspiro[5,5]undecatrienones

“…Additionally, with the reaction of N -propiolyl-benzimidazole holding the C2 phenyl group (in place of 4-methoxyphenyl), 1m was also investigated to verify the feasibility of either ipso -cyclization or ortho -cyclization. Notably, the reaction did not progress to provide either of the annulated products; instead, hydrolysis of propiolamide was observed to give 2-phenyl benzimidazole ( 6 ) …”

Highly Efficient Zn(L‐Pro)2 Catalyst for the Synthesis of 2‐Phenyl Benzimidazoles and 2‐Phenyl Benzothiazoles via Aerobic Oxygenation

“…[27,29] On the other hand, the traditional method for synthesizing benzothiazoles and benzimidazoles, [30,31] use Brønsted and Lewis acids as catalysts in an oxidative cyclization. Furthermore, the condensation reaction of o-phenylenediamine or o-aminothiophenol with a variety of aldehydes, acid chlorides, carboxylic acids, and nitriles in the presence of a variety of catalytic systems has been developed using Sm(OTf) 3 , [32] Ceric ammonium nitrate [CAN], [33] CeO 2 -ZrO 2 , [34] VOSO 4 , [35] Zn 3 (BTC) 2 MOF, [36] K 2 S 2 O 8 , [37] Bi(NO 3 ) 3 , [38] 4-MethoxyTEMPO, [39] Fe/ionic liquid, [40] Chlorotrimethylsilane, [41] via electrosynthesis, [42] hydrotalcite, [43] and hexamethylenetetramine-bromine complex. [44] While the above-mentioned reports were successfully completed employing a variety of catalysts or reagents, these methods have some drawbacks, including the use of expensive catalysts, toxic reagents and solvents, long reaction times, the formation of side products, the use of strong oxidizing reagents, stoichiometric quantities, and the use of metal salts, all of which are harmful to the environment.…”

“…On the other hand, the traditional method for synthesizing benzothiazoles and benzimidazoles, [30,31] use Brønsted and Lewis acids as catalysts in an oxidative cyclization. Furthermore, the condensation reaction of o‐phenylenediamine or o‐aminothiophenol with a variety of aldehydes, acid chlorides, carboxylic acids, and nitriles in the presence of a variety of catalytic systems has been developed using Sm(OTf) 3 , [32] Ceric ammonium nitrate [CAN], [33] CeO 2 ‐ZrO 2 , [34] VOSO 4 , [35] Zn 3 (BTC) 2 MOF, [36] K 2 S 2 O 8 , [37] Bi(NO 3 ) 3 , [38] 4‐MethoxyTEMPO, [39] Fe/ionic liquid, [40] Chlorotrimethylsilane, [41] via electrosynthesis, [42] hydrotalcite, [43] and hexamethylenetetramine‐bromine complex [44] …”

A one-pot synthesis of benzimidazoles via aerobic oxidative condensation of benzyl alcohols with o-phenylenediamines catalyzed by [MIMPs]+Cl-/NaNO2/TEMPO

“…44–47 In particular, some ILs as catalysts exhibit good performances in the oxidative condensation of aldehydes or benzylamines with o -phenylenediamine to give benzimidazoles. 46–49 More particularly, some Brönsted acid ILs as catalysts performed well in condensation reactions to afford benzimidazoles and bis(arylidene)cycloalkanones. 50,51…”