Fullerene triazolines

The synthesis of the triazolino[4, 5 l,2][60]fullerene 204, a novel donor-acceptor dyad exhibiting efficient electron-transfer dynamics, was reported by Guldi et al. (44) (Scheme 9.44). The azido tetrathiafulvalene 203, on heating with [60]fullerene in o-dichlorobenzene at 60 °C, gave the triazoline 204 in 24%... 

Bellavia-Lund and Wudl (43) investigated the 1,3-dipolar cycloaddition of 2-(methoxyethoxy)methyl azide with [70]fullerene (199) (Scheme 9.43). Three isomeric triazolines 200-202 were obtained. Thermolysis of these triazolines gave the corresponding azafulleroids and fulleroaziridines, as a mixture, respectively. 

The aziridinofullerenes and azafulleroids obtained by Mattay et al. were subjected to further reactions to yield fullerene adducts of the second generation. As a model compound 4-methyl-l,2,4-triazoline-3,5-dione (NMTAD) 187, which is one of the most reactive dienophiles for Diels-Alder reactions, was selected. Sheridan et al. studied the photoinduced [4 + 2] cycloadditions of NMTAD to arenes [295], With alkenes, however, NMTAD reacts in photoinduced cycloadditions in a [2 + 2] fashion under formation of diazetidines [296], Both the sulfonyl-azafulleroids (185) and aziridinofullerene (186) were irradiated at 420 nm to give both the same [2 + 2] cycloadduct 186 (Scheme 71) [291], This indicates that at a certain stage rearrangements must be involved. 

A Ci-symmetric hexakis-adduct of C6o including an azahomofullerene substructure (addition pattern analogue of homo[60]fullerene derivative ( )-26, Scheme 1.2) was obtained as a side product upon nitrogen extrusion from a fullerene derivative bearing five Bingel type addends and a fused triazoline arranged in a pseudo-octahedral manner.120... 

Similarly to the reaction with diazomethane, [3 + 2] cycloaddition of alkyl azides to C70 affords three constitutionally isomeric adducts (87, 88, and ( )-89) 46.226,227 Thermal elimination of N2 from the fullerene-fused triazolines showed a preference for the formation of 6-5 open azahomofullerene structures (types 90 and ( )-91) as compared to the 6-6 closed aziridine isomers corresponding to 92 and 93 (Scheme 1.9).226,227... 

Scheme 6. Formation of methano- and imino[60]fullerenes out of pyrazolines or triazolines...

Irradiation of the pyrazoline mixture 12, 13, and ( )-14 yielded methanofullerenes 15 and 16 (7 1) with a closed transannular 6 - 6 bond besides minor amounts of a third constitutional isomer (17), whereas thermolysis of the same mixture gave 17 and inherently chiral ( )-18 (4 l),both constituting core-modified fullerenes [76] (Scheme l).With open transannular 6-5 bonds , the functionalized regions of 17 and ( )-18 resemble methanoannulene sub-structures. [3 + 2]Cycloaddition of alkyl azides to C70 affords triazolines which are isolable when the temperature does not exceed ca. 50 °C. Similar to the reaction with diazomethane, three constitutionally isomeric adducts were observed [77,113], and the regioisomer of type 19 [113] with the substituent of the heterocycle located above the apex of C70, predominated over its regioisomer of type 20 in two in-... 

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