Selective preparation of oxygen-rich [60]fullerene derivatives by stepwise addition of tert-butylperoxy radical and further functionalization of the fullerene mixed peroxides.
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).
Huang
Shaohua
S
Key Laboratory of Bioorganic Chemistry and Molecular Engineering of the Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Xiao
Zuo
Z
Wang
Fudong
F
Gan
Liangbing
L
Zhang
Xiang
X
Hu
Xiangqing
X
Zhang
Shiwei
S
Lu
Mujian
M
Pan
Qinqi
Q
Xu
Li
L