Table 1.

Initial discovery and condition optimizations.^[a]

entry	catalyst	solvent	conditions	yield[b]	2a/2a’
1	Ph3PAuNTf2	toluene	60 °C, 11 h	20%[c]	2.4
2	Ph3PAuNTf2	benzene	60 °C, 11 h	40%[d]	2.4
3	Ph3PAuNTf2	DCE	60 °C, 11 h	52%	1.9
4	Ph3PAuNTf2	PhCl	60 °C, 11 h	44%	2.1
5	Ph3PAuNTf2	DCE	80 °C, 11 h	60%	1.9
6	IPrAuNTf2	DCE	80 °C, 11 h	81%	4.3
7	Cy-JohnPhosAuNTf2	DCE	80 °C, 11 h	60%	2.7
8	t-BuXPhosAuNTf2	DCE	80 °C, 11 h	66%	8.6
9	(ArO)3PAuNTf2[e]	DCE	80 °C, 11 h	73%	2.0
10	AuCl3	DCE	80 °C, 11 h	<20%	-
11	t-BuXPhosAuNTf2	anisole (0.2 M)	80 °C, 5 min	>95%[f]	6.5
12	t-BuXPhosAuNTf2	anisole (0.2 M)	40 °C, 1.5 h	>95%	5.2
13	t-BuXPhosAuNTf2	anisole (0.2 M)	−20 °C, 12 h	>95%	3.9

^[a][1] = 0.05 M.

^[b]Estimated by ¹H NMR using diethyl phthalate as the internal reference.

^[c]Regioisomers of 3 were formed due to reaction with solvent toluene.

^[d]2,3-diphenylindole (4) was formed in 10% yield.

^[e]Ar = 2,4-di-tert-butylphenyl.

^[f]Isolated yield: 89%.