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.

Five membered N-heterocycles are significant targets in organic synthesis because of their ubiquitous existence in bioactive natural products and pharmaceuticals. Over the past decade a compelling attractiveness has grown to develop rhodium complex catalysed efficient and atom-economic chemistry to access structurally diverse N-heterocyclic frameworks. This present review enlightens notable progresses and advances in synthesis of 5-membered N-heterocycles via rhodium catalysed cascade reactions (annulations, CÀ H/CÀ C activation, cycloaddition, rearrangement, cyclization, metathesis) from 2018-2021.[a] D.

An efficient one-pot Michael addition-cyclization reaction has been developed for the synthesis of 6H-chromeno[4',3' : 4,5] imidazo[1,2-a]pyridine under microwave irradiation method. The current protocol paves the way for the synthesis of twenty number of structurally diversified imidazo[1,2-a]pyridines in high yield by the reaction of substituted 2-aryl-3-nitro-2Hchromenes with 2-aminopyridines using anhydrous iron (III)chloride. This current protocol is the first report of the preparation of this medicinally significant highly substituted 6H-chromeno[4',3' : 4,5]imidazo[1,2-a]pyridine derivatives under microwave irradiation in good to high yields. The tolerance of a wide range of functional groups, operational simplicity and short reaction times are the significant advantages of this protocol.

Polysubstituted furans are widespread structural motifs, extensively dispersed in natural products, in numerous bioactive compounds, pharmaceuticals, agrochemicals and organic functional materials. Hence, the development of rapid and competent methodologies for the synthesis of multisubstituted furans has drawn much attention over the years. This review summarizes the synthesis of polysubstituted furans using transition‐metal catalyzed, transition metal‐free, photochemical and electrochemical approaches with plausible mechanistic insights. In each reaction, the highest yields of di‐, tri‐ or tetrasubstituted furans are highlighted and some applications of the methodology towards the synthesis of natural products and biologically active compounds are mentioned. The present review highlights the recent progresses in the synthesis of polysubstituted furans reported from 2019 to 2023.

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