Azomethine ylides diasteroselective

On the other hand, the use of the suitable combination of a metal salt, chiral ligand, and base promotes at low temperature the formation in situ of chiral A-metalated azomethine ylides from the corresponding iminoester and the subsequent selective cycloaddition onto the fullerene cage. Thus, the P,S chiral ligand Fesulphos along with copper(II) acetate directs the addition toward the formation of the stereoisomer (25, 55)-2-alkoxycarbonyl-5-arylpyrrolidino[3,4 l,2][60]fullerene with complete cis diasteroselectivity and enantiomeric excesses up to 93% (Scheme 34.9). 

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