Table 2.

Control Experiments Establishing an Acid-Catalyzed Mechanism for the Rearrangement of Furan 5b to Indole 6

entry	modificationa	time	NMR yield of 6(%)b
1	none	6 h	86
2	hν = 350 nm	5 min	84
3	no light	6 h	trace
4	0.5 equiv of K2CO3	6 h	trace
5	no light, 3 mol % of Rh2(esp)2	6 h	27
6	no light, 10 mol % of TsOH	1 h	89

^aNo light = protected from light with aluminum foil.

^bYields determined by ¹H NMR (400 MHz) using bibenzyl as an internal standard.