Screening of reaction conditions^a,f.

Entry	Iodine source	Oxidant	Solvent	Yieldb (%)
1	KI	O2	CH3CN	4
2	KI	O2	1,4-Dioxane	91
3	KI	Open air	1,4-Dioxane	90
4	TBAI	Open air	1,4-Dioxane	85
5 c	I 2	Open air	1,4-Dioxane	96
6	NIS	Open air	1,4-Dioxane	78
7c	I2	Open air	THF	45
8c	I2	Open air	Isopropyl ether	4
9c	I2	Open air	EtOAc	Trace
10c	I2	Open air	CH3CN	66
11c	I2	Open air	MeOH	Trace
12c	I2	Open air	H2O	22
13c,d	I2	Open air	1,4-Dioxane	80
14c,e	I2	Open air	1,4-Dioxane	90

^aUnless otherwise stated, all the reactions were conducted in solvent (1 mL) using 1a (0.12 mmol) and 4a (0.1 mmol) with stirring for 24 h at 50 °C. This was followed by the addition of iodine source (0.02 mmol) and oxidant (O₂ balloon), and the solution was then stirred for 48 h at room temperature.

^bIsolated yield.

^cThe reaction was conducted in the presence of 10 mol% iodine source.

^dFirst step was conducted at 40 °C for 24 h.

^eFirst step was conducted at 60 °C for 24 h.

^fThe dr value is >25 : 1 for all the isolated products.