Table 5.

Catalytic activities of acidic compounds on formation of 5-dodecylindolino[60]fullerene.

Catalyst	Type	Time	Yield of 8a / % a
Montmorillonite K10	clay mineral	6 h	56.7
Sepiolite	clay mineral	6 h	63.8
BiCl3	Lewis acid	2 h	50.3
BF3·OEt2	Lewis acid	2 h	0 (C60 was given)
p-TsOH	Brønsted acid	over 5 days	0 (C60 was given)
Amberlyst 15®	Brønsted acid	over 5 days	trace (C60 was given)

^a Isolated yields, estimated from HPLC areas. Reaction condition: C₆₀O 100 mg, 0.136 mmol; 4-dodecylaniline 355 mg, 1.357 mmol; Catalyst ×2,000 wt%, chlorobenzene 100 mL, 100 °C.