Aerobic {Mo₇₂V₃₀} nanocluster‐catalysed heterogeneous one‐pot tandem synthesis of benzimidazoles

Abstract

A novel heterogeneous one‐pot protocol is developed for tandem aerobic synthesis of benzimidazoles through dehydrogenative coupling of primary benzylic alcohols and aromatic diamines co‐catalysed by Keplerate‐type {Mo72V30} polyoxometalate and N‐hydroxyphthalimide (NHPI). The catalytic system also works well for the synthesis of benzimidazoles using benzaldehydes, as commonly used starting materials, in the absence of NHPI. The high activity of the solid nanocluster provides standard conditions avoiding current limitations of oxidation methods including high catalyst loadings. The spectral results and leaching experiments revealed that the nanocapsule preserved its structural integrity after being reused in consecutive runs.

Cucurbit[6]uril-Supported Fe3O4 Magnetic Nanoparticles Catalyzed Green and Sustainable Synthesis of 2-Substituted Benzimidazoles via Acceptorless Dehydrogenative Coupling

“…In this report, an acceptorless dehydrogenative coupling (ADC) methodology has been proved to be a versatile and sustainable method for the synthesis of 2-substituted benzimidazoles because hydrogen and water are the only byproducts generated under homo- and heterogeneous catalysis. − The ADC reactions of alcohols and diamines have been employed for the synthesis of several 2-substituted benzimidazoles with spectacular success. Many complexes of noble metals (Ru and Ir) − and transition metals (Mn, Pd, Cu, Ni, and Co) have been used as catalysts for the ADC reactions. − …”

Recent Advances in N‐Hyrdoxypthalimide: As a Free Radical Initiator and its Applications

“…NHPI along with {Mo 72 V 30 } polyoxometalate was used by Rezaeifard and team to synthesize various substituted benzimidazoles by the oxidation of primary benzylic alcohols coupled with aromatic diamines in presence of molecular oxygen. The reaction mechanism involved the formation of PINO radical as depicted in Scheme 9 [32] …”

Bimetallic CoMoO4@C nanorod catalyzes one‐pot synthesis of benzimidazoles from benzyl alcohol and o‐phenylendiamine without alkali

“…[1] In addition, benzimidazoles were important building blocks in natural products, pharmaceuticals, and organic/polymeric materials, especially for biological and pharmacological properties including antibacterial, antifungal, antiinflammatory, antiulcer, anticancer, and anti-HIV activities. [2][3][4] Typically, the traditional synthetic approach for these chemicals was the condensation of 1,2-diaminobenzene with carboxylic acids or their derivatives (acyl chlorides, acids, anhydrides, amides, and nitriles), under strongly acidic in elevated temperatures conditions (>200 C). [5][6][7][8][9][10][11][12] However, it had to be pointed out that leaving groups and additives led to low atom efficiency, which violated the green chemistry concept.…”