Table 2. Optimization of the Cycloisomerization of 4a^a.

entry	catalyst	solvent	t (min)	yield (%)b
1	PPh3AuCl/AgNTf2	toluene	60	–c
2	AgNTf2	toluene	30	79
3	AgNTf2	THF	>240	–c
4	AgNO3	toluene	40	91
5	Ag2CO3	toluene	40	97
6	AgOAc	toluene	40	94
7	AgOTf	toluene	50	91
8	AgSbF6	toluene	30	91
9	CuI	toluene	>1 d	traces
10	PtCl2	toluene	>1 d	traces
11	Ag2CO3	toluene/THF 4:1	4 h	94
12d	Ag2CO3	toluene	40	97

^aReaction conditions: 0.13 mmol of 3a, 10 mol % of catalyst, 1.3 mL solvent, rt.

^bYield of isolated 4a after flash column chromatography.

^cComplicated mixture of products which could not be separated.

^dIn the presence of 20 mol % A and 40 mol % (S)-N-Boc alanine.