Solvent-free phase transfer catalysis under microwaves in fullerene chemistry. A convenient preparation of N-alkylpyrrolidino[60]fullerenes

[60]Fullerene Amino Acids and Related Derivatives

“…For example, the reaction of [60]fullerene with the chiral O-protected L-4-hydroxyproline derivative (47) and formaldehyde gives the fulleroproline derivatives (48a and 48b) in a diastereoselective fashion 43 . The presence of the bulky tert-butyldiphenylsiloxy (OTBDPS) group favours attack of the 1,3-dipole with the bulky OTBDPS group facing away from the fullerene sphere, resulting in the major product being adduct (48b).…”

N‐Unsubstituted and N‐Arylated Fulleropyrrolidines: New Useful Building Blocks for C60 Functionalization†

“…As expected, introduction of the longer aliphatic chain greatly increases the solubility of the corresponding C 60 derivative (≥5 mmol/L) in solvents like chloroform, dichloromethane and THF. It has been reported that 2-arylated fulleropyrrolidines could be alkylated 17,18 and arylated. 19 Considering that alkyl groups have lowered electron-with-drawing ability and steric hindrance, 18 the corresponding pyrrolidines should be of higher basicity and nucleophicility than their aryl-bearing counterparts.…”

Microwave Irradiation: An Important Tool to Functionalize Fullerenes and Carbon Nanotubes

“…Remarkably, the basicity of pyrrolidino[60]fullerenes is six orders of magnitude lower than that of the corresponding pyrrolidine [65] due to the presence of the C 60 cage and, as a consequence, the reactivity of the nitrogen atom is very low. Nevertheless, it has been shown that NH-pyrrolidino[60]fullerenes can be efficiently functionalized at the nitrogen atom by using a combination of microwave irradiation techniques and PTC in the absence of solvent (Scheme 19) [66], an approach that enables the synthesis of N-alkylpyrrolidino[60]fullerenes (59a-e). Solvent-free PTC has been successfully applied to a wide range of organic reactions and it is very useful when this technique is combined with microwave irradiation, especially in anionic reactions that proceed slowly, give low yields or require harsh conditions.…”