Zn-Proline Catalyzed Selective Synthesis of 1,2-Disubstituted Benzimidazoles in Water

Abstract

Zn-proline (5 mol%) performs as a novel water-soluble and recyclable Lewis acid catalyst for the selective synthesis of 1,2-disubstituted benzimidazoles from wide range of substituted o-phenylenediamines and aldehydes in moderate to excellent isolated yields (42-92%) using water as solvent at ambient temperature.

Reusable Cobalt(III)‐Salen Complex Supported on Activated Carbon as an Efficient Heterogeneous Catalyst for Synthesis of 2‐Arylbenzimidazole Derivatives

“…In the next step, we studied the generality and selectivity of the catalyst for the condensation of electronically divergent aromatic aldehydes with o-phenylenediamine. In all cases, the reaction was clean and carried out within 25 min to 7 h. All products were characterized by IR, 1 H NMR, 13 C NMR and mass spectrometry. As shown, both aldehydes bearing electron-donating and electron-withdrawing substituents afforded the desired benzimidazoles in excellent yields (Table 4).…”

“…[5] Various oxidative reagents such as nitrobenzene (high-boiling point oxidant/solvent), [10] 1,4-benzoquinone, [11] air, [5] InA C H T U N G T R E N N U N G (OTf) 3 , [1b] PhIA C H T U N G T R E N N U N G (OAc) 2 , [12] Zn-proline, [13] heteropoly acids, [14] thionyl chloride-treatment, [15] DDQ, [16] electron-deficient olefins, [17] benzofuroxan, [18] MnO 2 , [19] PbA C H T U N G T R E N N U N G (OAc) 4 , [20] oxone, [21] NaHSO 3 , [22] H 2 O 2 /HCl [23] and Na 2 S 2 O 5 [24] have been employed. Because of the availability of a vast number of aldehydes, the condensation of phenylenediamines with aldehydes has been extensively used.…”

Chemoselective Synthesis of 2-Aryl-1-arylmethyl-1H-benzo[d]imidazoles Using Indion 190 Resin as a Heterogeneous Recyclable Catalyst

“…34 But one of the major margins of these methodologies is that they show poor selectivity in terms of Nsubstitution, which results in the formation of two compounds i.e, the formation of a 2-substituted benzimidazole along with 1,2-disubstituted benzimidazole as a mixture. [24][25][26]28,[33][34][35][36][37][38][39][40] Herein, we report the synthesis of 1,2-disubtituted benzimidazoles (3) by the reaction of an o-phenylenediamine (1) and various aromatic aldehydes (2) in the presence of Indion 190 resin (Scheme 1).…”

Synthesis, characterization and crystal structure of 2-(4-(methylthio)phenyl)-1H-benzo[d]imidazole

“…In addition, benzimidazole derivatives are effective against the human cytomegalovirus (HCMV) [5] and are also efficient selective neuropeptide Y Y1 receptor antagonists [6]. Most of the described methods for the synthesis of benzimidazoles make use of volatile organic solvents and involve solid-phase synthesis via o-nitroanilines [7][8][9][10] or the condensation of o-phenylenediamines with carboxylic acid derivatives [11], aldehydes [12][13][14][15][16][17] and aryl halides [18].…”