Tunable Copper-Catalyzed Reaction of C₆₀ with 2-Ethoxycarbonylacetamides and Subsequent BF₃·Et₂O-Mediated Isomerization of the Generated Dihydrofuran-Fused Fullerenes to Fulleropyrrolidinones

Abstract

A tunable copper-catalyzed reaction of C 60 with 2-ethoxycarbonylacetamides using air as the oxidant has been explored, which selectively affords methanofullerenes (2) and dihydrofuran-fused fullerenes (3) under the CuI/DMAP and CuCl/NMI catalytic systems, respectively. Furthermore, the generated dihydrofuran-fused fullerenes could be transformed to fulleropyrrolidinones (4 and 5) upon treatment with BF 3 •Et 2 O.

Copper-Catalyzed Reaction of C60 with Tertiary Amines for the Preparation of Spiro-Linked Methanofullerenes and Fullerenoalkanals

“…No reaction occurred by even prolonging the reaction time to 20 h, indicating that CuI alone could not trigger the reaction (Table , entry 1). Next, the combination of CuI with different ligands was tried because the catalytic system varied greatly with the substrate structure, as has been observed in our previous research . Using Phen (1,10-phenanthroline) or Bpy (2,2′-bipyridine) as ligands afforded the anticipated product 2a in 12 and 37% yield, respectively (Table , entries 2 and 3).…”

“…On the other hand, the remarkable potential of organofullerenes in materials and biomedical science, electronic devices, and nanotechnology has made organic modification of fullerenes receive more attention. , In this respect, the transition metal-promoted or -catalyzed reaction has represented a powerful tool to functionalize fullerenes including radical reactions, C–H activation, and asymmetric reactions . Over the past few years, Cu­(I/II)-promoted transformation of C 60 has gradually attracted increasing attention. , We have been interested in this field and have developed several new methods for the functionalization of C 60 . Most recently, we reported an interesting CuI-catalyzed reaction of C 60 with aminoalcohols .…”

Selective formation of dihydrofuran fused [60] fullerene derivatives by TEMPO mediated [3 + 2] cycloaddition of medium chain β-keto esters to C60

“…15,16 In reaction of b-keto esters with C 60 different furan-fused fullerene derivatives were obtained. Enolatemediated C-H activation occurs in the presence of a base 17 usually with the aid of Cu(I)/Ag(I), 18,19 Pd(II)/Cu(II) mixtures, 20,21 Mn(III). 22 Recently, Gao and Chen described the synthesis of furan-fused fullerenes by controlling the addition sequence of base and iodine as oxidant.…”

“…Based on the above experimental results and literature data, reaction mechanism pathway involving fullerenyl cation is proposed (Scheme 3). 21,27 Finally, enolization and intramolecular nucleophilic addition of 8 afford the furan-fused fullerenes 3 as the product of the reaction. Using the optimized reaction conditions the substrate scope was investigated with keto esters 2a-d and furano fused fullerenes 3a-d were obtained in moderate or good yields 34-54% (Scheme 2).…”