Chiral Fullerenes from Asymmetric Catalysis

Chirality is an important and fascinating aspect which, however, has not been properly addressed in fullerenes science.^[1] Recent results from our group support the basic idea that the chemistry of fullerenes is not completely developed and that a variety of fundamental reactions, mainly involving transition metals and organocatalysts are helpful in order to address issues such as the regio- and the stereo-selectivity, so far unsolved in the fullerene functionalization.

We have recently reported on the synthesis of enantiomerically pure fullerenes with a total control of the stereochemical outcome. The suitable choice of the chiral metal catalyst ([Cu(II) or Ag(I)] in combination with a variety of different chiral ligands) directs the 1,3-dipolar cycloaddition of N-metalated azomethyne ylides on C₆₀, on C₇₀ and on endohedral metallofullerenes with high levels of site-, regio-, diastereo- and enantio-selectivity.^[2] Furthermore, we have also shown that chiral fullerenes can be efficiently prepared by using organocatalysis.^[3] In this communication, the most recent synthetic results involving endohedral fullerenes as well as their cis-transisomerization will be discussed.

References:

[1] E. E. Maroto, M. Izquierdo, S. Reboredo, J. Marco-Martínez, S. Filippone, N. Martín "Chiral Fullerenes from Asymmetric Catalysis" Acc. Chem. Res. 2014, 47, 2660−2670.

[2] (a) Filippone, S., Maroto, E.E., Martín-Domenech, A., Suarez, M. and Martín, N., Nature Chem., 2009, 1, 578; (b) Maroto, E. E.; de Cozar, A.; Filippone, S.; Martin-Domenech, A.; Suarez, M.; Cossio, F. P.; Martín, N. Angew. Chem. Int. Ed., 2011, 50, 6060; (c) Sawai, K.; Takano, Y.; Izquierdo, M.; Filippone, S.; Martín, N.; Slanina, Z.; Mizorogi, N.; Waelchli, M.; Tsuchiya, T.; Akasaka, T.; Nagase, S. J. Am. Chem. Soc., 2011, 133, 17746; (d) Maroto, E.E., Filippone, S., Martín-Domenech, A., Suarez, M. and Martín, N., J. Am. Chem. Soc. 2012, 134, 12936; (e) E. E. Maroto, S. Filippone, M. Suárez, R. Martínez-Álvarez, A. de Cózar, F. P. Cossío, N. Martín, J. Am. Chem. Soc., 2014, 136, 705.

[3] (a) J. Marco-Martinez, V. Marcos, S. Reboredo, S. Filippone, N. Martín, Angew. Chem. Int. Ed., 2013, 52, 5115. (b) J. Marco-Martínez, S. Reboredo, M. Izquierdo, V. Marcos, J. L. López, S. Filippone, N. Martín, J. Am. Chem. Soc., 2014, 136, 2897.