Selective Preparation of Oxygen-Rich [60]Fullerene Derivatives by Stepwise Addition of tert-Butylperoxy Radical and Further Functionalization of the Fullerene Mixed Peroxides

Abstract

tert-Butylperoxy radicals add to C(60) selectively to form multi-adducts C(60)(O)(m)(OO(t)Bu)(n) (m = 0, n = 2, 4, 6; m = 1, n = 0, 2, 4, 6) in moderate yields under various conditions. Visible light irradiation favors epoxide formation. High concentration of tert-butylperoxy radicals mainly produces the hexa-homoadduct C(60)(OO(t)Bu)(6) 6; low concentration and long reaction time favor the epoxy-containing C(60)(O)(OO(t)Bu)(4) 7. The reaction can be stopped at the bis-adducts with limited TBHP. A stepwise addition mechanism is discussed involving mono-, allyl-, and cyclopentadienyl C(60) radical intermediates. m-CPBA reacts with the 1,4-bis-adduct to form C(60)(O)(OO(t)Bu)(2) and C(60)(O)(3)(OO(t)Bu)(2). The C-O bond of the epoxy ring in 7 can be cleaved with HNO(3) and CF(3)COOH. Nucleophilic addition of NaOMe to 7 follows the S(N)1 and extended S(N)2' mechanism, from which four products are isolated with the general formula C(60)(O)(a)(OH)(b)(OMe)(c)(OO(t)Bu)(d). Visible light irradiation of the hexa-adduct 6 results in partial cleavage of both the C-O and O-O bonds of peroxide moieties and formation of the cage-opened compound C(60)(O)(O)(2)(OO(t)Bu)(4). All the fullerene derivatives are characterized by spectroscopic data. A single-crystal structure has been obtained for an isomer of C(60)(O)(OH)(2)(OMe)(4)(OO(t)Bu)(2).

Preparation of [5,6]‐ and [6,6]‐Oxahomofullerene Derivatives and Their Interconversion by Lewis Acid Assisted Reactions of Fullerene Mixed Peroxides

“…The 1 H NMR spectrum of 6 was identical to that reported previously. [14] 1-Ethoxy-2,4-dihydroxy-11,15,30-tri-tert-butylperoxy-oxa 3,4 3 ·x H 2 O (3 mg) was added to a solution of 4 (11 mg, 0.010 mmol) in CH 2 Cl 2 (3 mL). The mixture was stirred at room temperature Progress of the reaction was monitored by TLC.…”

“…Keywords: epoxides · fullerenes · hemiketals · isomerization · peroxides fullerene and hydroxylated fullerene derivatives with welldefined structures. [14] In light of the well-established and rich chemistry of classical peroxides, fullerene mixed peroxides appear to be excellent precursors for compounds with potential applications. Here we report the Lewis acid induced formation and single-crystal X-ray diffraction analysis of [5,6]-and [6,6]-oxahomo[60]fullerene derivatives (fullerene hemiketals).…”

Fullerene Doping: Preparation of Azafullerene C59NH and Oxafulleroids C59O3 and C60O4

“…The mixed heterofullerenes C 56 X 2 Y (X = N, P; Y = O, S) [21] are shown to be as chemically stable as C 60 .We have reported the preparation of a series of fullerenemixed peroxides C 60 (O) x (OOtBu) y (x = 0, 1; y = 2, 4, 6). [22] Further investigation of the reactivity of these peroxides indicates that they are excellent precursors for selective fullerene skeleton bond cleavage. A number of open-cage fullerene derivatives, some of which have a orifice large enough to encapsulate a water molecule, were prepared starting from either C 60 (O)(OOtBu) 4 or C 60 (OOtBu) 6 .…”

“…In our previous studies, we have shown that any of the three single bonds in the C 60 À OÀOÀtBu moiety could be cleaved in the presence of Lewis acids, such as BF 3 and FeCl 3 . [22,23] The selectivity depends on the reaction conditions and the local structure of the fullerene-mixed peroxides. Cleavage of the C 60 À O will give the bromo derivative 10 in one step; cleavage of the O À O and O À tBu bonds will results in the intermediates A and B, respectively.…”

Ferric perchlorate-mediated radical reactions of [60]fullerene

“…The transformation of ArC 60 -H into ArC 60 -OAc by Mn(OAc) 3 ·2H 2 O was also successfully realized [36]. Other transition metal salts such as CoCl 2 dppe [17], Cu(OAc) 2 ·H 2 O [18,27], Pb(OAc) 4 [31,37], TBADT [(n-Bu 4 N) 4 [42,43] have also been employed in fullerene chemistry. However, the free radical reactions of C 60 promoted by relatively cheap and easily available Fe(ClO 4 ) 3 had not been reported in fullerene chemistry before we initiated our study.…”