Formation of fullerooxazoles from C61HPh(3-): the regioselectivity of heteroatom additions.
The formation of fullerooxazoles from C(61)HPh(3-) has been examined in benzonitrile (PhCN), m-methoxybenzonitrile (m-OCH(3)PhCN), m-tolunitrile (m-CH(3)PhCN), and o-tolunitrile (o-CH(3)PhCN), where cis-1 bisadducts with Ph-, m-OCH(3)Ph-, m-CH(3)Ph-, and o-CH(3)Ph-substituted cyclic imidate next to the phenylmethano are formed as evidenced by various characterizations. Interestingly, only regioisomers 2a-d with the oxygen atom bonded to C4/C5 and the nitrogen atom bonded to C3/C6 are generated as demonstrated by heteronuclear multiple bond coherence (HMBC) NMR, while the alternative regioisomers 3a-d, which have the oxygen and nitrogen atoms at C3/C6 and C4/C5, respectively, are not formed from the reactions, even though the DFT (density functional theory) calculations have predicted that the energy differences between the two types of regioisomers are very small, with regioisomers 3a-d actually having lower energies than 2a-d. The results are rationalized by the charge distributions of C(61)HPh(3-), where computational calculations have shown that the negative charges on C4 and C5 are greater than those on C3 and C6, indicating that the exhibited site selectivity of heteroatoms is a result of the charge-directed addition process.
State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Graduate School of Chinese Academy of Sciences, 5625 Remin Street, Changchun, Jilin 130022, China.
Fang-Fang
FF
Li
Wei-Wei
WW
Yang
Guo-Bao
GB
He
Xiang
X
Gao