Table 1.

Optimization of reaction conditions^a

Entry	Activating species	Base	I source	Yield of 3a (%)b
1c	Tf2O	/	I2	trace
2	Tf2O	/	I2	50
3	Tf2O	BDMEP	I2	69
4	Tf2O	BDMEP	I2	32
5	Tf2O	DBU	I2	trace
6	TMSOTf	BDMEP	I2	n.d.
7	BF3·Et2O	BDMEP	I2	n.d.
8	(CF3CO)2O	BDMEP	I2	n.d.
9	Tf2O	BDMEP	NIS	33
10	Tf2O	BDMEP	ICl	27
11	Tf2O	BDMEP	TBAI/NaI	n.d.
12d	Tf2O	BDMEP	I2	66
13e	Tf2O	BDMEP	I2	35
14f	Tf2O	BDMEP	I2	83

“n.d.” stands for “not detected”.

Tf₂O trifluoromethanesulfonic anhydride, TMSOTf trimethylsilyl trifluoromethanesulfonate, BDMEP 2,6-Di-tert-butylpyridine, DBU 1,8-Diazabicyclo[5.4.0]undec-7-ene, NIS N-Iodosuccinimide, TBAI Tetrabutylammonium iodide.

^aReaction conditions: 1a (0.20 mmol, 1.0 equiv), 2a (0.40 mmol, 2.0 equiv), activating species (0.20 mmol, 1.0 equiv), base (0.40 mmol, 2.0 equiv), CHCl₃ (2.0 mL), 60 °C, 3 h, then I source (0.40 mmol, 2.0 equiv) was added for 18 h. ^bIsolated yield.

^cI source was added at first and stirred at 60 °C for 21 h.

^d2a (0.30 mmol, 1.5 equiv) was used.

^e2a (0.20 mmol, 1.0 equiv) was used.

^fCHCl₃ (1.0 mL) and Tf₂O (0.21 mmol, 1.05 equiv) were used.