Prato reaction

The amino acid sarcosine reacts with paraformaldehyde when heated at reflux in toluene to an ylide which reacts with a double bond in a 6,6 ring position in a fullerene via a 1,3-dipolar cycloaddition to yield a N-methylpyrrolidine derivative or pyrrolidinofullerene or pyrrolidino[[3,4:1,2]] [60]fullerene in 82% yield based on C60 conversion.

[2] In one application a liquid fullerene is obtained when the pyrrolidone substituent is a 2,4,6-tris(alkyloxy)phenyl group [3] although a small amount of solvent is still possibly present.

This reaction was derived from the work of Otohiko Tsuge [4] on Azomethine Ylide Chemistry developed in the late 1980s.

[7] When the amino acid is modified with a glycine chain the resulting nanotubes are soluble in common solvents such chloroform and acetone.

The N-methylpyrrolidine derivative reacts poorly (5% yield) and for a successful reaction the nitrogen ring also requires substitution in the α-position with methyl, phenyl or carboxylic ester groups.