This review focuses on providing comprehensive highlights of the recent synthetic pathways of imidazo[1,2‐a]pyridines, assisted through transition metal‐catalyzed reactions, multi‐component reactions, cyclization, condensation, microwave‐assisted reactions, heteroannular and photocatalytic reactions. Among the heterocyclic groups, imidazo[1,2‐a]pyridines are considered as privileged structures because of their occurrence in many natural products. In this review, we have summarized the recent advances in the synthesis of imidazo[1,2‐a]pyridines from 2016 to 2021 from various substrates. This review will provide new initiatives to the chemists towards the synthesis of imidazo[1,2‐a]pyridines and all frequent challenges associated with the reported methods.

An organocatalyzed asymmetric Michael addition reaction has been established as the most relevant and dynamic research area for the construction of chiral carbon‐carbon and carbon‐heteroatom bond. In the current scenario, rapid revolutions on asymmetric Michael addition to nitroolefins have been explored by taking advantage of newly developed chiral organocatalysts. Moreover, nitroolefins have proven as well‐known Michael acceptors for providing various structurally essential nitro‐functionalized frameworks. In addition to this, remarkable stereoselectivity has been achieved in this asymmetric process by following different mechanistic pathways that involve enamine, iminium ion intermediate formation and bifunctional H‐bonding interaction. So, we have discussed the recent advancements of organocatalytic Michael addition reactions to α, β‐unsaturated nitroolefins from the year 2016 to 2020.

The current study aimed to identify a new strategy of FeCl 3 catalyzed multicomponent synthesis of substituted 2H-chromene-fused pyrrole derivatives.A series of chromene-based pyrrole prepared by employing an array of 3-nitro-2H-chromenes, aniline, and acetylacetone in toluene under microwave irradiation. Using FeCl 3 as a prompt catalyst and microwave irradiation to synthesize 2H-chromene-fused pyrrole motifs significantly reduces the reaction time and facilitates to high yields (83%-95%). Structure of all synthesized compounds analyzed by spectroscopic analysis. One-pot reaction, short reaction period, and simple experimental procedure are the fascinating properties associated with this protocol. The in vitro antibacterial activity of the entire series was assessed against Staphylococcus aureus and Escherichia coli. Out of all the compounds, 15b and 15h revealed most excellent potency against both the bacterial strains relative to the reference gentamicin. Docking study was employed to determine the possible binding orientation of DNA gyrase with the active sites of chromene-fused pyrrole analog. The docking results show that compounds 15b and 15h have higher binding affinity with energy −8.00 and −8.80 kcal/mol. These results illuminate the mode of binding progression and provide an esteemed pathway for the design and the structural modification of chromene-fused pyrroles as a newly advanced class of antibacterial agent.

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Smallest ring size, high ring strain, and more reactivity of cyclopropene have brought the attention of researchers for chemical exploration. In this context, the chemistry of cyclopropene and cyclopropenone has exponentially grown over the last few years. This present review focuses on the most recent developments in cyclopropane chemistry.