DMSO: An Efficient Catalyst for the Cyclopropanation of C60, C70, SWNTs, and Graphene through the Bingel Reaction

Dimethyl sulfoxide (DMSO) with sodium carbonate (Na2CO3) is an effective catalyst system for C60 cyclopropanation through the Bingel reaction. Various bromomalonic esters, brominated β-keto esters, brominated 1,3-diketones, and other bromo-substituted active methylene compounds can react with C60 in the presence of DMSO and Na2CO3 to achieve excellent yields of the corresponding methanofullerenes at 10 °C. Moreover, this proposed methodology has been also employed successfully to functionalize [70]fullerene, single-walled carbon nanotubes (SWNTs), and graphene. This protocol is beneficial because it involves short reaction time, high yield, and a simple procedure. Additionally, this method does not need a strong base, such as sodium hydride and 1,8-diazabicyclo[5,4,0]undec-7-ene, because inexpensive Na2CO3 can be the catalyst.