On the Thermal Stability of [60]Fullerene Cycloadducts: Retro-Cycloaddition Reaction of 2-Pyrazolino[4,5:1,2][60]fullerenes
文摘
2-Pyrazolino[4,5:1,2][60]fullerenes undergo a thermally induced retro-cycloaddition process whoseefficiency is influenced by the nature of the C-substituent. C-Aryl-N-Aryl-2-pyrazolino[60]fullerenes(2a-d) poorly undergo a thermal retro-cycloaddition reaction even in the presence of a strong dipolarophileor a metal Lewis acid which, in contrast to other fullerene derivatives, shows their remarkable thermalstability. C-Alkyl-N-Aryl-2-pyrazolino[60]fullerenes (2e-f) show a different behavior, being morevulnerable to the presence of copper triflate and leading to the retro-cycloaddition product (pristine C60)in good yield.