Azafullerene arylation

Arylated azafullerenes are also accessible from the heterofullerene precursors 6 and 33 by thermal treatment in the presence of aromatics and air (Scheme 12.12) [3]. Although the yields are lower than those starting from 2, one reaction step can be saved. Conversely, if the reaction is carried out in 1-chloronaphthalene at 220 °C, 34 is obtained in an isolated yield of 46%. 

Fig. 17. More trapping products of the reaction 22 28. Trapping of azafullerenyl radical intermediate 1 by hydroquinone leads to the formation of hydroaza[60]fullerene 34. Trapping of intermediate azafulleronium 2 by anisole yields arylated azafullerene 35...

Recently, it was found that when the reaction is carried out in the presence of a large excess of anisole and air, arylated azafullerene 35 can be obtained in 38 % yield [68] (Fig. 18). Compound 35 was also obtained, but in a much lower yield, directly from bisazafulleroid 8, when the reaction shown in Fig. 16 was carried out in the presence of anisole and air. When the same reaction was carried out in pure 1-chloronaphthalene at 220 °C, a mixture of arylated products 36 was obtained in 46% isolated yield [68]. 

Thermal treatment of the dimer with anisole, toluene, and 1-chloronaphtha-lene in the presence of a large excess of pTsOH and air leads to the formation of mono-arylated azafullerenes in 78-90% isolated yields [68]. The reaction with anisole and toluene yield para-substitution products 35 and 39, while 1-chloro-naphthalene is substituted at various positions (Fig. 21). The reaction does not take place in the absence of air or pTsOH. The reaction is presumed to proceed through electrophilic aromatic substitution by C59N, which was proposed as being formed via thermal homolysis of the dimer, followed by oxidation with O2. 

Very recently, Reuther and Hirsch have found that 35, 39, and yet another arylated azafullerene 40, react with iodine monochloride in a reaction closely analogous to the one found by Taylor and co-workers, yielding tetra-chlorinated compounds 41,42, and 43, respectively, in 50-60% yields [70,71]. An interesting point is that the five-membered ring containing the nitrogen atom adopts the... 

Aryl-azafullerenes with ICI. The reverse reaction takes place with excess PPhj in ODCB at25°C... 

---

See also in sourсe #XX -- [ ]

---