Intramolecular Wittig Reaction of α,α'-Dioxocycloalkylidenetributylphophoranes: Formation and Trapping of Cycloalkyn-2-ones with Five- and Six-membered Rings
Reaction of the title phophoranes with homophthalic anhydride or 1,3-diphenylisobenzofuran in the presence of Me3SiCl gave the corresponding Diels-Alder adducts, indicating the transient intermediacy of cycloalkyn-2-ones with five- and six-membered rings.