Herstellung von enantiomerenreinem C76 durch Retro-Bingel-Reaktion

Abstract

Zufällig entdeckt wurde bei elektrochemischen Untersuchungen zur Stabilität von Anionen von 1 eine präparativ nützliche Methode: die Retro‐Bingel‐Reaktion, eine elektrochemische Methode zur Entfernung der Bis(alkoxycarbonyl)methano‐Bücken von Methanofullerenen. Sie wurde dazu verwendet, um die ersten Proben von enantiomerenreinem D2‐C76 mit gesicherter optischer Reinheit herzustellen.

Nucleophilic Additions

“…This is consistent with an addition to a double bond of a pole corannulene unit (1,2-addition), leading to 1,2-dihydro [70]fullerene derivatives. This is consistent with an addition to a double bond of a pole corannulene unit (1,2-addition), leading to 1,2-dihydro [70]fullerene derivatives.…”

Organofullerene Materials

“…Equally important to Bingel functionalization of fullerenes has been the observation that reduction of such formed adducts with two electrons causes rapid methanofullerene ring opening and reverse Michael-type addition, to yield starting fullerene as product [47]. Thus, the retro-Bingel reaction has allowed fullerene-cyclopropanated adducts to serve as protecting groups for further chemical transformations.…”

Parent Fullerenes

“…Certain to confident structure assignment [263] was possible for [74-D 3h ]-fullerene [264], [76-D 2 ]fullerene, [210] [78-C 2v (1) ]fullerene [211,256,258], [78-C 2v(2) ]fullerene [256,258], [78-D 3 ]fullerene [211,256,258], [80-D 2 ]fullerene [253], [82-C 2 ]fullerene, [84-D 2d ]fullerene, [260,261] and [84-D 2 ]fullerene [256,258,261,262]. Optically pure isomers of [76-D 2 ]fullerene were obtained by functionalization of (±)-[76-D 2 ]fullerene with an enantiopure chiral addend, separation of the resulting diastereoisomers, and subsequent removal of the functionality [266]. Since only one isomer of each C 60 , C 70 and C 76 is formed, in the following the indication of symmetry will be omitted.…”