Amino Acid Ester and Carbon Disulfide C₆₀ Functionalization

Significance

A novel method for the functionalization of C₆₀ with amino acid esters and CS₂ is reported. The technique involves stirring the hydrochloride salt of the amino acid ester with C₆₀ in CS₂ at room temperature with excess Et₃N. Four amino acid esters were tested (1a-d) with major product (2a-d) yields ranging between 30% and 40% and minor product yields (3a-d) between 0% and 6%. The reaction is proposed to proceed through isothiocyanate anion intermediates 5a-d which cyclize with the fullerene and are then either protonated to form the major product or attack 4a-d to form the minor product.