The First Synthesis of a Methano[60]fullerene with an Electron-Donating Group at the Methano-Bridge Carbon:  Synthesis and Reaction of Aminomethano[60]fullerene

Abstract

[reaction: see text] Aminomethano[60]fullerene was synthesized for the first time as a trifluoromethanesulfonic acid salt by applying the Curtius rearrangement of azidocarbonylmethano[60]fullerene as the key reaction. Aminomethano[60]fullerene thus obtained was found to be able to react with various acyl chlorides to afford the corresponding amides.

[60]Fullerenyl amino acids and peptides: a review of their synthesis and applications

“…Treatment of 91 with TfOH provided the amine salt 92, which was coupled to various acyl chlorides 93 to generate the corresponding amide derivatives 94 (Scheme 16). 28 Thermal ring opening of methylenecyclopropanone ketal 95 in chlorobenzene in the presence of [60]fullerene followed by silica gel hydrolysis of the resulting ketene acetal gave a mixture of cycloadducts 96 and 97. 29 The corresponding fullerenyl amino ester derivatives 98 and 99 were subsequently prepared from 96 by DCC coupling (Scheme 17).…”

Ring-Opening Reaction of Cyclopropanated [60]Fullerenes: Unexpected Transformation of Methano[60]fullerenes Having an Electron-Donating Group on the Methano-Bridge Carbon

“…This is most likely because (i) methano[60]fullerenes themselves are attractive targets even at present as described above, and (ii) most of the precedented methano[60]fullerenes possess an electron-withdrawing group on their methano-bridge carbon, which efficiently stabilizes the cyclopropane moiety toward a ring-opening reaction . Recently, we have reported the first synthesis of methano[60]fullerenes bearing an electron-donating group (amino group) on the methano-bridge carbon, in which the rearrangement of an electron-withdrawing group on the methano-bridge carbon was the key reaction . Considering the electron-donating characteristic of the amino group, aminomethano[60]fullerenes would be suitable as the starting materials to realize our concept.…”

“…According to the procedure we have recently reported, seven kinds of aminomethano[60]fullerenes were prepared as trifluoromethanesulfonic acid (HOTf) salts ( 1a − g ·HOTf) …”

Fullerenes

“…42 The Curtius rearrangement of azidocarbonylmethano [60]fullerene in the presence of an alcohol results in the in situ formation of the carbamate which, when treated with trifluoromethanesulfonic acid, was converted to the insoluble salt of aminomethano [60]fullerene. 43 [60]Fullerene has been used to trap a new S-heterocyclic carbene via formation of the methanofullerene. 44 Usefully functionalized cyclopentenone derivatives of [60]fullerene have been prepared by hydrolysis of the [60]fullerene product obtained from cycloaddition in the presence of isonitriles and dimethyl acetylene dicarboxylate.…”