Hui-Juan Wang

A Protocol for the Preparation of 2,5-Diaryl Fulleropyrrolidines: Thermal Reaction of [60]Fullerene with Aromatic Aldehydes and Arylmethanamines

Thermal reaction of [60]fullerene with various arylmethanamines in the presence of aromatic aldehydes under air conditions afforded a series of rare 2,5-diaryl fulleropyrrolidines. Intriguingly, the obtained fulleropyrrolidines exhibited different stereoselectivity. N-unsubstituted arylmethanamines exclusively produced 2,5-diaryl fulleropyrrolidines as cis isomers, while N-substituted arylmethanamines with rare exceptions always gave 2,5-diaryl fulleropyrrolidines as trans isomers. Theoretical calculations at the level of B3LYP/6-31G (d,p) were employed to elucidate the stereoselectivity of N-substituted 2,5-diaryl fulleropyrrolidines as trans isomers by investigating the transition-state structures of different cycloaddition pathways.

Facile access to 2,5-diaryl fulleropyrrolidines: magnesium perchlorate-mediated reaction of [60]fullerene with arylmethylamines and aryl aldehydes

The facile one-step reaction of [60]fullerene with arylmethanamines and aryl aldehydes in the presence of magnesium perchlorate under air conditions generated a series of scarce 2,5-diaryl fulleropyrrolidines in good to excellent yields. Intriguingly, all the formed 2,5-diaryl fulleropyrrolidines were confirmed only as cis isomers and thus displayed high stereoselectivity. In addition, the type of aryl aldehyde was found to have a great correlation with the formation of different 2,5-diaryl fulleropyrrolidines. Aryl aldehydes without electron-withdrawing groups always afforded exclusively the desired 2,5-diaryl fulleropyrrolidines, while aryl aldehydes connecting electron-withdrawing groups unexpectedly produced symmetrical 2,5-diaryl fulleropyrrolidines besides the anticipated fulleropyrrolidines. A plausible formation mechanism for the 2,5-diaryl fulleropyrrolidines was proposed.

DMAP-Mediated Synthesis of Fulleropyrrolines: Reaction of [60]Fullerene with Aromatic Aldehydes and Arylmethanamines in the Absence or Presence of Manganese(III) Acetate

A series of scarce fulleropyrrolines were synthesized via DMAP-mediated one-step reaction of [60]fullerene with commercially inexpensive aromatic aldehydes and arylmethanamines in the absence or presence of manganese(III) acetate. In the case of aminodiphenylmethane, novel 2,5,5-trisubstituted fulleropyrrolines could be easily obtained without the addition of manganese(III) acetate. As for arylmethanamines without α-substitutions, the addition of manganese(III) acetate was required to suppress the formation of fulleropyrrolidines, in order to generate the desired 2,5-disubstituted fulleropyrrolines. Two tautomers were produced as expected when different aryl groups (Ar1 ≠ Ar2) from aromatic aldehydes and arylmethanamines were employed in the synthesis. A plausible reaction mechanism for the formation of fulleropyrrolines is proposed.

TEMPO-Mediated Synthesis of Tetrahydropyridinofullerenes: Reaction of [60]Fullerene with α-Methyl-Substituted Arylmethanamines and Aldehydes in the Presence of 4-Dimethylaminopyridine

A series of scarce tetrahydropyridinofullerenes were synthesized by the metal-free-mediated reaction of [60]fullerene with cheap and easily available α-methyl-substituted arylmethanamines and aldehydes in the presence of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) and 4-dimethylaminopyridine (DMAP) in moderate to good yields comparable to the previously reported data for most monoadducts. The in situ generation of azadienes played a crucial role in the successful synthesis of tetrahydropyridinofullerenes. A plausible reaction mechanism was proposed to elucidate the reaction process.

Synthesis of 2-Aryl-5-alkyl-fulleropyrrolidines: Metal-Free-Mediated Reaction of [60]Fullerene with Aromatic Aldehydes and Inactive Primary Amines

The metal-free-mediated thermal reaction of [60]fullerene with aromatic aldehydes and inactive primary amines bearing electron-donating groups at the α-position afforded a series of 2-aryl-5-alkyl-fulleropyrrolidines, including the scarce 2-aryl-5-benzyl-fulleropyrrolidines as a mixture of cis and trans isomers. With rare exceptions, the mixture of cis and trans isomers could be easily isolated by column chromatography, with a preference of cis isomers as major products. A plausible mechanism for the formation of fulleropyrrolidines is also proposed.

Stereoselective synthesis of cyclopentafullerenes: the reaction of [60]fullerene with aldehydes and triethylamine promoted by magnesium perchlorate

The magnesium perchlorate-mediated reaction of [60]fullerene with aldehydes and triethylamine under air conditions afforded a series of rare cyclopentafullerenes in moderate to good yields with high stereoselectivity. A plausible reaction mechanism was suggested to elucidate the formation of cyclopentafullerenes.

Metal-free-mediated synthesis of fulleropyrrolines by the reaction of [60]fullerene with β-substituted ethylamines

The reaction of [60]fullerene with β-substituted ethylamines under air conditions afforded unexpected fulleropyrrolines with trisubstituted alkene functional groups in moderate yields. The conversion of β-substituted ethylamines to their corresponding aldehydes played a crucial role in the successful synthesis of fulleropyrrolines. Promoted by p-toluenesulfonic acid, the obtained fulleropyrroline could (1) be converted back to [60]fullerene in nearly quantitative yield and (2) further react with 1,3-propanediol to generate fullerene-fused dioxepane.