Azides fullerene reactions

Several studies have demonstrated the successful incoriDoration of [60]fullerene into polymeric stmctures by following two general concepts (i) in-chain addition, so called pearl necklace type polymers or (ii) on-chain addition pendant polymers. Pendant copolymers emerge predominantly from the controlled mono- and multiple functionalization of the fullerene core with different amine-, azide-, ethylene propylene terjDolymer, polystyrene, poly(oxyethylene) and poly(oxypropylene) precursors [63,64,65,66,62 and 66]. On the other hand, (-CggPd-) polymers of the pearl necklace type were fonned via the periodic linkage of [60]fullerene and Pd monomer units after their initial reaction with thep-xy y ene diradical [69,70 and 71]. 

A mixture of sulfonyl-azafulleroid 168 and sulfonylaziridino-fullerene 169 was obtained by reaction of sulfonyl azide with CgQ in o-dichlorobenzene at 160 °C (Scheme 4.30) [173]. The ratio of the two products depends on the substituent of the sulfonyl group. In all cases the aziridino fullerene can be obtained from the azafulleroids by irradiation. 

Systematic investigations of twofold additions of malonates to C70 revealed that the second addition takes place at one of the five a-bonds of the unfunctionalized pole [17, 26], With achiral, C2v-symmerical malonate addends, three constitutionally isomeric bisadducts are formed An achiral one (C2v-symmetrical 1), and two chiral ones (C2-symmetrical 2 and 3), which are obtained as pairs of enantiomers with an inherently chiral addition pattern (Figure 13.5). Twofold addition of chiral malonates leads to the formation of five optically active isomers, two constitutionally isomeric pairs of C2-symmetrical diastereomers and a third constitutional C2-symmetrical isomer (Figure 13.5). Twofold additions of azides to C70 lead to diazabis[70]homo-fullerenes, which served as starting material for the synthesis of bis-(aza[70]-fullerenyl) (Cg9N)2 (Chapter 12) [27]. As further bisadditions, addition reaction to C70 [2+2]cycloaddition of electron-rich bis(diethylamino)ethyne and 1-alkylthio-2-(diethylamino)ethynes [28] and the addition of transition metal fragments have been reported [29-32],... 

Averdung et al. also obtained several aziridinofullerenes by the reaction of C60 with acylnitrenes, generated by photolysis of aroylazides 85a-d, leading to the fullerene adducts 86a-d (Scheme 34) [260], In a typical experiment a solution of C6o and a five-fold excess of azide 85a-d in oxygen free 1,1,2,2-tetra-chloroethane was irradiated for 60 min in Pyrex tubes using a RPR 100 Rayonet... 

Banks et al. reported the formation of the expected [6,6]-closed aziridino-fullerene by the reaction of C6o and singlet oxycarbonylnitrenes [271], In addition, small amounts of unexpected closed [5,6]-closed adducts were postulated [272], In further investigations, Banks et al. studied the irradiation of C6o and ethyl azid-oformate 109 in benzene leading to a 4 1 mixture of two major products (Scheme... 

Recently, in another synthetic approach for the construction of efficient fullerene-tetrathiafulvalene dyads, a fullerotriazoline dyad (fullerotriazolines are thermally labile intermediates that are formed upon reaction of fullerenes with azides [243]) possessing a substituted tetrathiafulvalene functionality was reported [244]. 

It is known [1, 11], that the addition of organic azides leads to the formation of 5,6-open monoorganofullerenes (monoazahomofullerenes). Moreover, it is shown, that in contrast to the reactions of 6,6-closed monoorganofullerenes with azides, the cycloaddition of azides to azahomofullerenes can result to the formation of one bis(organo)fullerenes isomer as the predominate product [12]. However, the question is whether regioselective cycloaddition of azide to monoazahomofullerenes depends on the structure of azide organic fragment. The present communication is devoted to the search of the answer to this question, because a little amount of isolated communications did not answer the question [13-17]. 

Earlier we have studied the reactions of fullerene Cgo with the isocyanurato-, phosphoryl-, pyrimidino-, nitropyrimidino-, quinoxalin-, benzopyrazine substituted azides [18-24]. As a result, both 6,6-, 5,6-closed and 5,6-open organofullerens were synthesized, and the series of them were reduced electrochemically easier than the pristine fullerene C6o- Now the reactions of fullerene C6o with isocyanurato- and nitropyrimidine substituted azides were used for the search of the answer to delivered question. For solving the problem the substituents in positions 1 and 3 of the isocyanurate ring and the number of methylene units between ring and azide group in isocyanurate containing azides were varied. 

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... 

A single di(azahomo)[60]fullerene 25 (see Section 14.06.3.1) was prepared by the reaction between [60]fullerene and isocyanurato-substituted azide 90 (Equation 17) <2002RCB1491>. 

In contrast to the N-MEM (N-alkyl) analogue (see Sect. 2.2.2), N-aryl-aza-fiilleroids, obtained from the thermal reaction of aryl azides with 50, can be photochemically isomerized to azirenofullerenes [51]. This closely resembles the difference in the photochemical behavior of C-aryl- and C-alkyl fulleroids obtained from the reaction of diazo compounds with Qo (e.g. [5,6] CgiHj is photochemically stable). After some initial studies (see for example [52-55]), the addition of azides and nitrenes to C o has been investigated and used for the preparation of a series of functional fullerene derivatives by a number of other investigators, but their work is not relevant in relation to the preparation of aza[60] fullerene. The addition of azides to fullerenes has been brie% reviewed previously [56-58]. 

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