The furan structure is a ubiquitous subunit in a variety of bioactive natural products and synthetic materials, including agrochemicals and pharmaceuticals. Thus, the development
of efficient and concise synthetic methods that allow access to functionalized furan derivatives, and particularly furan fused heterocyclic compounds, remains an important task
in modern organic chemistry. Coumarins are an extremely important family of heterocyclic compounds owing to their presence in a large variety of biologically active substances and their use as valuable agents for pharmaceuticals and fine chemicals. Over the past several decades, synthesis and screening of coumarin compounds for drug discovery has been a vital subject of constant interest in organic and medicinal chemistry.
We described three tricyclic oxygen containing heterocycle synthesis, where an arene both an alcohol and an alkyne functionality underwent three distinct pathways catalyzed by different metal salts. Starting from 4-hydroxycoumarin and propargyl alcohol derivatives, furo[3,2-c]coumarins was accomplished by a Cu(II) salts, while furo[2,3-b]chromones could be accessed via a Fe(III) salts. Pyrano[3,2-c]coumrains also was accomplished by a Bi(III) salts. This method provides a flexible and efficient route to substituted furocoumarins, furochromones and pyranocoumarins respectively.