Synthesis of C60-fused tetrahydrothiophene derivatives via nucleophilic cycloaddition of thiocyanates.

Nucleophilic cycloaddition of thiocyanates 1a-e with C60 in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene afforded C60-fused 2-iminotetrahydrothiophene derivatives 2a-e and methanofullerenes 3a-d. The product distributions were highly sensitive to the substrates employed. The 2-iminotetrahydrothiophene derivatives 2a-e could be further manipulated by hydrolysis and acetylation to give 2-oxotetrahydrothiophene derivatives 4a-e and 2-acetamidotetrahydrothiophene derivatives 5a-e. A possible reaction mechanism for the formation of products 2a-e and 3a-d was proposed.