One-pot synthesis of new thio-derivatives of C60 with the unexpected formation of a thiazolidine-fulleropyrrolidine

One-pot Prato reactions of C-60 with amino acids and aldehydes afford five new fullerene derivatives, including two unexpected thiazolidine and oxazolidine fulleropyrrolidines. In particular, L-cysteine (1), paraformaldehyde and C-60 in refluxing toluene solution affords an unexpected new thiazolidine-fulleropyrrolidine derivative 3 (instead of 2) via 1,3-dipolar cycloaddition, whose structure was characterized in detail. A possible reaction mechanism for the formation of 3 is proposed. These suggest that the active hydrogen of S-H in 1 is essential for the formation of the thiazolidine ring in 3. To confirm further this conclusion, reactions of C-60 with different amino acids (5, 7) and aldehydes (3-(methylthio)proplonaldehyde (9) and 2-thiophenaldehyde (11)) were also studied, resulting in the synthesis of other three new thio-derivatives of C-60 (6, 10, 12) as well as an oxazolidine fulleropyrrolidine (8).