Copper-mediated synthesis of fullerooxazoles from [60]fullerene and N-hydroxybenzimidoyl cyanides.

A novel and efficient copper-mediated [3 + 2] heteroannulation reaction of [60]fullerene with N-hydroxybenzimidoyl cyanides has been developed for the synthesis of fullerooxazoles. A possible reaction mechanism involving unique C-CN and N-OH bond cleavages and subsequent C-OH bond formation for N-hydroxybenzimidoyl cyanides is proposed to explain the generation of fullerooxazoles. In addition, the formed fullerooxazoles can be further electrochemically transformed into amidated 1,2-hydrofullerenes.

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

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.

A copper-promoted synthesis of epoxy-bridged [60]fullerene-fused lactones and further derivatization.

A facile copper-promoted decarboxylative annulation of [60]fullerene (C60) with two identical α-oxocarboxylic acids via an unprecedented cascade addition pathway has been exploited to synthesize the unique epoxy-bridged C60-fused lactones for the first time. Further transformations into the rare epoxy-bridged C60-fused hemiacetals and bicyclic-fused 1,2,3,4-adducts as well as application in a perovskite solar cell device of the obtained products have also been demonstrated. The structures of the epoxy-bridged C60-fused lactones and derived reductive products have been unequivocally established by single-crystal X-ray crystallography. Plausible reaction mechanisms leading to the observed products are proposed.

Cu(I)-Catalyzed Synthesis of [60]Fullerene-Fused Lactams and Further Electrochemical Functionalization.

A novel and efficient Cu(I)-catalyzed radical heteroannulation reaction of [60]fullerene (C60) with α-bromo acetamides has been disclosed for the direct synthesis of diverse C60-fused lactams. Furthermore, the formed C60-fused lactams can be served as a versatile platform for further electrochemical functionalization to prepare 1,2-, 1,4-, 1,2,3,16-, and 1,4,9,25-adducts of C60. In addition, a representative fullerene product has been applied as an overcoating layer of the electron-transporting layer in n-type perovskite solar cell.

Synthesis of Fullerotetrahydroquinolines via [4 + 2] Cycloaddition Reaction of [60]Fullerene with in Situ Generated Aza-o-quinone Methides.

An efficient [4 + 2] cycloaddition reaction of [60]fullerene with the in situ generated aza-o-quinone methides from N-(o-chloromethyl)aryl sulfonamides with the assistance of Cu2O has been developed to afford a series of fullerotetrahydroquinolines. This strategy exhibits a broad substrate scope and excellent functional group tolerance. A tentative reaction pathway for the formation of fullerotetrahydroquinolines is proposed on the basis of the experimental results.