Tunable Synthesis of Indeno[1,2-c]furans and 3-Benzoylindenones via FeCl₃-Catalyzed Carbene/Alkyne Metathesis Reaction of o-Alkynylbenzoyl Diazoacetates

An efficient synthesis of indeno[1,2- c ]furan and 3-benzoylindenone derivatives through a FeCl 3 -catalyzed carbene/alkyne metathesis reaction of o -alkynylbenzoyl diazoacetates is presented. Mechanistically, the key intermediate, vinyl iron carbene, is formed by 5 -exo-dig carbocyclization and terminated with a formal [3 + 2] cycloaddition or carbonylation. To the best of our knowledge, this is the first example in which FeCl 3 is used as a catalyst for a carbene/alkyne metathesis reaction. Finally, derivatization reactions were carried out to showcase the value of the products.