Table 1. Optimized reaction conditions ^a .

Entry	Variation from the “standard conditions”	Conv. of 1a b (%)	Yield b (%)
1	None	84	81(80) c
2	Without K2CO3	5	Trace
3	Without [RhCp*Cl2]2	0	0
4	Without AgOTf	55	50
5	1.5 equiv. of Cu(OAc)2	50	42
6	O2 and without Cu(OAc)2	5	0
7	135 °C instead of 120 °C	85	80
8	100 °C instead of 120 °C	66	65

^a The reactions were run on a 0.20 mmol scale in 0.5 mL of DCE.

^b Yields determined by ¹NMR spectroscopy using N-(4-methoxyphenyl)acetamide as the internal standard.

^c Yield of isolated products. Cp* = 1,2,3,4,5-pentamethylcyclopentadiene, and DCE = 1,2-dichloroethane.