Stereodivergent
Synthesis of Chiral Fullerenes by
[3 + 2] Cycloadditions to C<sub>60</sub>
- Publication date
- Publisher
Abstract
A wide
range of new dipoles and catalysts have been used in 1,3-dipolar
cycloadditions of N-metalated azomethine ylides onto C<sub>60</sub> yielding a full stereodivergent synthesis of pyrrolidino[60]fullerenes
with complete diastereoselectivities and very high enantioselectivities.
The use of less-explored chiral α-iminoamides as starting 1,3-dipoles
leads to an interesting double asymmetric induction resulting in a
matching/mismatching effect depending upon the absolute configuration
of the stereocenter in the starting α-iminoamide. An enantioselective
process was also found in the retrocycloaddition reaction as revealed
by mass spectrometry analysis on quasi-enantiomeric pyrrolidino[60]fullerenes.
Theoretical DFT calculations are in very good agreement with the experimental
data. On the basis of this agreement, a plausible reaction mechanism
is proposed