Highly Regio‐ and Stereoselective [2+3] Cycloadditions of Azomethine Ylides to [70]Fullerene

Abstract

AbstractPicolylamines and aromatic aldehydes were used as reagents to generate azomethine ylides that undergo highly regio‐ and stereoselective [2+3] cycloaddition reactions with [70]fullerene. Isolated pyrrolidinofullerenes were products of the ylide addition across the most reactive 8,25‐double bond in the carbon cage; other regioisomers were observed in small amounts or did not form at all. These reactions demonstrated unusually high stereoselectivity: 2′,5′‐disubstituted pyrrolidinofullerenes were represented almost entirely by cis isomers, whereas obtained 1′,2′,5′‐trisubstituted products were shown to be trans isomers. Cyclic voltammetry studies of the synthesised pyrrolidinofullerenes showed the existence of some electronic communication between the substituents in the pyrrolidine ring and the [70]fullerene cage. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)