170503-88-5Relevant articles and documents
Selective electrolytic removal of bis(alkoxycarbonyl)methano addends from C60 bis-adducts and electrochemical stability of C70 derivatives
Kessinger, Roland,Fender, Nicolette S.,Echegoyen, Lourdes E.,Thilgen, Carlo,Echegoyen, Luis,Diederich, Francois
, p. 2184 - 2192 (2007/10/03)
The novel mixed his-adducts of C60, (±)-4-(±)-8 and 9, with a bis(ethoxycarbonyl)methano addend (Bingel addend) and a second addend ([1,2]benzeno, but[2]eno, methaniminomethano, or diarylmethano) bridging 6,6-closed bonds of the carbon sphere were synthesized in two-step reactions. Each bis-adduct was exhaustively electrolyzed at the potential of the second fullerene-centered reduction step, resulting in the selective removal of the Bingel addend (retro-Bingel reaction) to produce the corresponding mono-adducts, which were isolated in yields of over 60%. These results open up the possibility of using the Bingel addend as a temporary protecting and directing group in the construction of multiple adducts of C60 with unusual addition patterns. The Bingel-type mono-adduct of C70 10 and the constitutionally isomeric bis-adducts 11, (±)-12, and (±)-13 were also included in this investigation. A large difference in the electrochemical behavior between C70, bis-adducts and the corresponding C60 derivatives was observed. Thus, the intramolecular "walk-on-the-sphere" isomerization which occurs readily with Bingel-type bis-adducts of C60 under the conditions of two-electron controlled potential electrolysis (CPE) is only a minor reaction pathway in the series of C70 derivatives. The latter preferentially undergo retro-Bingel reaction.
