Unexpected Diels–Alder reaction of [60]fullerene with electron-deficient ferrocenes as cyclopentadiene surrogates

Abstract

The unexpected Diels–Alder reaction of [60]fullerene (C₆₀) with ferrocenes bearing electron-withdrawing groups as cyclopentadiene surrogates has been developed to selectively afford single isomers of [2 + 4] cycloadducts of C₆₀. Mechanistic studies indicate that cyclopentadienes are in situ generated from electron-deficient ferrocenes in the presence of an oxidant and an acid, followed by [2 + 4] cycloadditions with dienophiles. A Michael addition reaction using a Grignard reagent has been utilized to transform the Diels–Alder adducts of C₆₀ into more stable fullerene derivatives.