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

Abstract

An efficient synthesis of indeno[1,2-<i>c</i>]furan and 3-benzoylindenone derivatives through a FeCl₃-catalyzed carbene/alkyne metathesis reaction of <i>o</i>-alkynylbenzoyl diazoacetates is presented. Mechanistically, the key intermediate, vinyl iron carbene, is formed by 5<i>-exo-dig</i> carbocyclization and terminated with a formal [3 + 2] cycloaddition or carbonylation. To the best of our knowledge, this is the first example in which FeCl₃ is used as a catalyst for a carbene/alkyne metathesis reaction. Finally, derivatization reactions were carried out to showcase the value of the products.