Synthesis of benzimidazoles and benzoxazoles using TiCl3OTf in ethanol at room temperature

Microwave-assisted practical and simple method for heterocyclization of o-phenylenediamine and aldehydes using DDQ as oxidant agent

“…A comparison of the present work with different reported works using various catalysts (10)(11)(12)(13)(29)(30)(31) in terms of reaction times and the yields of respective products is given in Table 4. As seen in Table 4, our procedure produced the benzimidazole derivatives with shorter reaction times, higher yield percentage of products, and easy work-up (Table 4, entry 1 vs. entries 2-9).…”

“…There are many protocols for benzimidazole synthesis through a general procedure including condensation of o-phenylenediamine with aldehydes under oxidative conditions (10)(11)(12)(13)(14)(15)(16)(17). Various oxidative agents such as 1,4-benzoquinone (18), MnO 2 (19), H 2 O 2 /HCl (20), benzofuroxane (21), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (22), ceric (IV) ammonium nitrate (CAN) (23), NaHSO 3 (24), and polymer-supported hypervalent iodine (25) have been applied.…”

Ultrasound and Nano‐Catalysts: An Ideal and Sustainable Combination to Carry out Diverse Organic Transformations

“…Benzimidazoles possess significant pharmacological efficacies that include antiviral, antibacterial, antiprotozoal, anti‐inflammatory, antimalarial, anticancer etc activities. A number of methods reported for the synthesis of benzimidazoles employing various catalysts such as polyaniline‐sulfate, nano‐In 2 O 3 , Zn 2+ ‐K10‐clay, TiCl 3 .OTf, nano‐MnFe 2 O 4 , NaY‐zeolite, Fe(HSO 4 ) 3 , MgCl 2 .6H 2 O etc . Longer reaction times (generally 2–24 h), moderate yields and the use of organic solvents such as MeOH, MeCN, CH 2 Cl 2 , CHCl 3 , DMF etc are some of the major demerits of these reported protocols.…”

Development of homogeneous polyamine organocatalyst for the synthesis of 2‐aryl‐substituted benzimidazole and benzoxazole derivatives

“…Because of the wide range of pharmacological and industrial applications of these heterocyclic compounds, wide variety of catalysts was reported for their synthesis. Most of the reported methods for the synthesis of these nitrogen containing heterocyclic compounds suffer from several disadvantages including the use of toxic catalysts and corrosive acids, occurrence of metal leaching and side reactions, need of additional oxidation step, use of reagents in large excess, long reaction time, and so forth 20–23 . Moreover, only a few reports are available for the base catalyzed synthesis of benzimidazoles and benzoxazoles 24–26 .…”