Solvent-dependent metal-free chemoselective synthesis of benzimidazoles and 1,3,5-triarylbenzenes from 2-amino anilines and aryl alkyl ketones catalyzed by I2

I2-mediated convenient ring-opening of simple gem-difluorocyclopropanes

We previously reported an efficient method for the ring-opening 1,3-difunctionalization of gem-difluorinated cyclopropanes (F2CPs) using KBr in the presence of ceric ammonium nitrate or potassium persulfate, resulting in the formation of 3-bromo-2,2-difluoropropanes with a bromine atom or a hydroxy group at the 1 position by the highly regioselective cyclopropane bond cleavage. In spite of the usefulness of this process, the concern of the use of these irritant oxidants and the insufficient reactivity of Br incorporated at the 1 position allowed us to modify this system to find out that the environmentally friendly as well as easy-to-handle reagent, an iodine molecule, works quite efficiently, enabling the successful introduction of not only a hydroxy group but also alkoxy, sulfenyl, and aryl groups at the 1 position of products.

Mo(0) carbonyl complexes bearing the bis(3,5-dimethylpyrazole) ligand: catalysis of the regioselective [2 + 2 + 2] cycloaddition of terminal alkynes to synthesize 1,3,5-isomers

The reaction between 1,3-bis(3,5-dimethylpyrazolylmethyl)hexahydropyrimidine L and Mo(CO)6 in CH3CN at 130 °C afforded a binuclear Mo(0) complex 1 containing a new macrocycle formed upon C-N bond cleavage in L in good yield. Conversely, a clean reaction takes place between L and [Mo(CO)4(COD)] in THF at 60 °C to give a new metalloligand complex [Mo(CO)4(κ2-N,N-L)] 2 containing a spectator pyrazole arm in 83% yield. Their structures were determined by X-ray diffraction methods, and a plausible mechanism is proposed for the C-N bond cleavage leading to complex 1. In view of a limited number of reports of catalysts for the synthesis of 1,3,5-trisubstituted benzene from the [2 + 2 + 2] cycloaddition of terminal alkynes, the catalytic application of complex 2 was explored. Interestingly, 14 terminal alkynes including those containing polar functional groups such as OH, NH2, and CHO among others were converted into their 1,3,5-isomers as the major products with a high regioselectivity ratio of >90 : 10 (1,3,5-/1,2,4-isomer) for most cases.

Regioselective C3Alkylation of Indoles for the Synthesis of Bis(indolyl)methanes and 3-Styryl Indoles

Herein, we describe an efficient transition-metal-free regioselective C3alkylation of indoles for the synthesis of bis(indolyl)methanes and 3-styryl indoles. Nitrobenzene is employed as the oxidant to oxidize the alcohols in the presence of a strong base and the reaction avoids the use of transition metals such as Ru and Mn. The protocol provides a favorable route to access biologically active compounds such as arundine, vibrindole A, and turbomycin B.

Unlocking the Pharmacological Potential of Benzimidazole Derivatives: A Pathway to Drug Development

Heterocyclic molecules have fascinated a massive interest in medicinal chemistry. They are heterocyclic compounds that have gained significance due to their diverse variety of pharmacological activities. Benzimidazole is a heterocyclic compound consisting of benzene and imidazole rings. The ease of synthesis and the structural versatility of benzimidazole make it a promising scaffold for drug development. Many biological actions of benzimidazole derivatives have been well documented, including antibacterial, antiviral, anticancer, anti-inflammatory, antitubercular, and anthelmintic properties. The mechanism of action of benzimidazole derivatives varies with their chemical structure and target enzyme. This review has explored numerous methods for producing benzimidazole derivatives as well as a broad range of pharmacological activities. SAR investigations are also discussed in this review as they provide crucial details regarding the essential structural qualities that benzimidazole derivatives must have in order to be biologically active, which could aid in the rational design of new drug candidates. Benzimidazole scaffold is an exclusive structure in drug design and discovery. Many new pharmaceutical drugs containing benzimidazole are anticipated to be available within the next ten years as a result of the extensive therapeutic applications of benzimidazole and its derivatives. This review inspired many researchers to develop more biologically active compounds bearing benzimidazole, expanding the scope of finding a remedy for other diseases. From this study, we concluded that 2-substituted benzimidazole was considered more extensively by researchers.