Table 1.

Optimization of reaction conditions.^a

Entry	Catalyst	Oxidantb	Solvent	Temp. (°C)	Yieldc (%)
1	CuI	PhIO	DMF	rt	trace
2	CuI	PhIO	CH3CN	rt	13
3	CuI	PhIO	DCE	rt	24
4	CuI	PhIO	toluene	rt	12
5	CuI	PhIO	DCE	40	35
6	CuI	PhIO	DCE	60	55
7	CuI	PhIO	DCE	reflux	48
8	CuCl	PhIO	DCE	60	49
9	CuBr	PhIO	DCE	60	50
10	CuOAc	PhIO	DCE	60	38
11	CuI	PIDA	DCE	60	46
12	CuI	PIFA	DCE	60	30

^aReaction conditions: Togni reagent 1 (1.2 mmol), 5a (1.0 mmol), catalyst (0.2 mmol), oxidant (1.5 mmol) in solvent (10 mL) unless otherwise stated. ^bThe oxidant was added to the reaction mixture after the substrate 5a was completely consumed (TLC analysis). ^cIsolated yield.