Oxazoline and Imidazoline Functionalization of a C₆₀ Dimer via the Reaction of C₆₀HBn and Aromatic Nitriles with a Bifunctional Hydroxide

Abstract

Oxazoline and imidazoline functionalization of a singly bonded C60 dimer is achieved via a one-pot reaction of C60HBn with OH(-) and aromatic nitriles, where the OH(-) not only functions as a Brønsted base that deprotonates C60HBn but also as a nucleophile that initiates the nucleophilic addition to the fullerene cage. The structures of the obtained oxazolinated and imidazolinated C60 dimeric compounds have been established by HRMS, UV-vis, and (1)H, (13)C, and HMBC NMR characterizations and computational calculations. The reaction mechanism is studied with the in situ vis-near-IR spectra, which shows that the use of I2 is crucial for the functionalization of the C60 dimer, indicating that it is likely the dimeric molecule rather than the fragment of the dimer that is involved in the reaction.

Methoxylation of Singly Bonded 1,4–1′,4′-BnC60–C60Bn Dimer: Preferential Formation of 1,4-C60 Adduct with Sterically Less Demanding Addends and Stability Difference between 1,2- and 1,4-OMe(Bn)C60

“…The covalent bond that directly connects the two C 60 cages is weak and easily cleaved, , consistent with the elongated bond length (1.576–1.645 Å) − , compared with the typical C–C bond length (1.541 Å) . In addition, the 1,4-positioned addends in the 1,4–1′,4′-RC 60 –C 60 R dimers may act as the directing groups in controlling the reaction site for the subsequent nucleophilic addition with the formation of a stable type of 1,4,15-R 3 C 60 – intermediate bearing the 10π indenyl anion resonance structure, similar to the cases of 1,4-R 2 C 60 derivatives, ,− making 1,4–1′,4′-RC 60 –C 60 R an interesting starting material for fullerene functionalization. Here, we report the methoxylation of 1,4–1′,4′-BnC 60 –C 60 Bn ( 3 , Scheme ), which exhibits different regiocontrol compared with that of functionalizing C 60 directly.…”

“…Considering that 1,4,15-R 3 C 60 – monoanionic intermediate with the 10π indenyl resonance subunit is typically formed when 1,4-R 2 C 60 is subjected to nucleophilic addition, ,− it is rational to assume that anionic intermediate A with the 1,4,15-configuration (Figure ) is formed via the methoxylation of 3 , where the methoxy is positioned at the para site with respect to the benzyl group judging from the structure of 2 . Figure a shows the optimized structure of intermediate A , and Figure b shows the HOMO distribution of the intermediate obtained with Gaussian09 at the B3LYP/3-21G level.…”

Reductive Benzylation of Singly Bonded 1,2,4,15-C60 Dimers with an Oxazoline or Imidazoline Heterocycle: Unexpected Formation of 1,2,3,16-C60 Adducts and Insights into the Reactivity of Singly Bonded C60 Dimers

“…We have recently reported the synthesis of singly bonded C 60 dimers with a 1,2,4,15-configuration that bear an oxazoline or imidazoline heterocycle on one of the carbon cages and one benzyl (Bn) group on each individual C 60 cage (compounds 1 and 2 in Figure ) . These dimeric molecules are subjected to reductive cleavage of the C 60 –C 60 bond, , generating monomeric tris-organo[60]­fullerene monoanions bearing a heterocycle with a 1,2,4-configuration.…”

Synthesis of (MeO)2Bn2C70: Regiochemistry of 2-fold Additions to C70 with Addends That Are Preferential for Ortho Addition and Capable of Para Addition

“…Previous work on multiple nucleophilic additions to C 60 and C 70 has shown that electronic factors such as the electrophilic Fukui functions f k + , , NBO charge distribution, and LUMO composition analysis of the 1-fold addition adducts are important in understanding the regioselectivity of the 2-fold nucleophilic addition reactions. Calculations on the electrophilic Fukui functions f k + , NBO charge distribution, and LUMO composition of 1-Bn-2-MeOC 70 ( 2 ) and 2-MeO-5-BnC 70 ( 4 ) were performed to study the regioselectivity of the reaction, which all predicted a similar result in that compound 6 was more feasible to form over the 2 and 12 o’clock isomers as the respective carbon atom was more electrophilic compared with the counterparts.…”