Tamura Cyclization of Rauhut–Currier (RC)‐Adducts of Nitroalkenes With Homophthalic Anhydrides for the Synthesis of Functionalized Tetralones and Naphthoquinones

A base‐mediated synthesis of functionalized tetralones and naphthoquinones via a [4 + 2] Tamura cycloaddition as the key step is disclosed here. The reaction of homophthalic anhydride with Rauhut‐Currier adducts of nitroalkenes takes divergent pathways after the initial Tamura cycloaddition, depending on the reaction conditions. While functionalized tetralones are the exclusive products in the presence of Et ₃ N in acetonitrile under an inert atmosphere at room temperature, Cs ₂ CO ₃ ‐mediated reaction under an O ₂ atmosphere facilitated the formation of functionalized naphthoquinone through a radical pathway. Additionally, the synthetic utility of the methodology has been demonstrated by synthesizing a functionalized dihydrophenanthrene and other selective functionalization products by taking advantage of the ketoalkyl side chain of the tetralone derivatives.