A Detailed Review on C ‐Fused Furan/3,4‐Fused Furan Analog and its Potential Applications

Abstract c ‐fused furan and their derivatives are widely used as essential components of agrochemicals, bioregulators, dyes, essential skin and hair oils, cosmetics, flavouring agents, photosensitizers in industry and also show a broad range of biological activity. To the best of our knowledge, as of yet, no review has been published that covers the entire synthetic pathway leading to the formation of just c‐fused or 3, 4‐fused furans. In this review, we outline the various pathways for bicyclic, tricyclic, and polycyclic c ‐fused furans, along with their detailed mechanisms, concrete examples, and biological activity. We have focused particularly on the synthetic route to medicine, natural products, and their analogues, such as c ‐fused furanoditerpenes isospongiadiol, radermachol, a potential folk medicine ingredient, furo[3,4]quinolin‐4(5H)‐ones core, an inhibitor of lymphoma, bhimamycin B, hibiscone‐c core moiety of antibiotic lactonamycin, and analogue of natural product furanether A/ furanether B. Previous approaches and recent methods are described including metal‐free, transition metal, bio‐catalyst, and multi‐substrate approaches with mechanisms. The review covers the literature for more than six decades and presents an overview of the synthesis of different c ‐fused furans and their utility in various disciplines such as synthetic chemistry, medicinal chemistry, and drug discovery.