Screening of reaction conditions^a,g.

Entry	Iodine source	Oxidant	Solvent	Yieldb (%)
1	I2	TBHP	CH3CN	82
2c	NaI	TBHP	CH3CN	84
3 c	KI	TBHP	CH 3 CN	86
4c	NH4I	TBHP	CH3CN	72
5c	nBu4NI	TBHP	CH3CN	80
6c	NIS	TBHP	CH3CN	83
7c	KI	TBPB	CH3CN	54
8c	KI	DTBP	CH3CN	23
9c	KI	NaClO2	CH3CN	28
10c	KI	K2S2O8	CH3CN	32
11c	KI	H2O2	CH3CN	76
12c	KI	TBHP	DMF	Trace
13c	KI	TBHP	THF	82
14c	KI	TBHP	1,4-Dioxane	Trace
15c	KI	TBHP	MeOH	68
16c	KI	TBHP	H2O	63
17c,d	KI	TBHP	CH3CN	55
18c,e	KI	TBHP	CH3CN	73
19c,f	KI	TBHP	MeOH	65
20c,f	NH4I	TBHP	MeOH	50
21c,f	nBu4NI	TBHP	MeOH	70
22c,f	NIS	TBHP	MeOH	52
23 c , f	nBu 4 NI	H 2 O 2	MeOH	77

^aUnless otherwise stated, all the reactions were conducted in solvent (1 mL) using 1a (0.1 mmol) and 2a (0.1 mmol) with stirring for 24 h at 50 °C, this was followed by the addition of iodine source (0.01 mmol) and oxidant (0.2 mmol), and the solution was then stirred for 24 h at room temperature.

^bIsolated yield.

^cThe reaction was conducted in the presence of 20 mol% iodine source.

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

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

^fFirst step was conducted at room temperature for 24 h.

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