TABLE 3.

Optimization of intramolecular EOC reaction conditions ^a .

Entry	R	M	Oxidant	Solvent	T (oC)	dr b	Yield c
1	Me	TBS	CAN	CH3CN/THF	0	8.7:1	77%
2	Et	TBS	CAN	CH3CN/THF	0	8:1	74%
3	iPr	TBS	CAN	CH3CN/THF	0	4.9:1	69%
4	tBu	TBS	CAN	CH3CN/THF	0	12:1	68%
5	iBu	TBS	CAN	CH3CN/THF	0	6.4:1	62%
6	iPr	TES	CAN	CH3CN/THF	0	5.8:1	64%
7	iPr	TIPS	CAN	CH3CN/THF	0	6.8:1	64%
8	iPr	TBS	CuCl2	CH3CN/THF	–78 to rt	--	21% (50%) d
9	iPr	TBS	Cu(acac)2	CH3CN/THF	–78 to rt	--	--
10	iPr	TBS	FeCl3	CH3CN/THF	–78 to rt	--	23% (54%) d
11	iPr	TBS	AgF, PhBr	CH3CN	Rt	--	no reaction
12	iPr	TBS	PhI(OH)OTs	DCM	–78	12:1	61%

^aReactions were carried out with 6 (0.08 mmol), CAN (0.24 mmol), and NaHCO₃ (0.48 mmol) in CH₃CN/THF (0.1 M, 4:1) at 0°C under N_2.

^bDetermined ratio of 2′ and 2 by ¹H NMR.

^cIsolated yields of 2 and 2′ after purification by column chromatography.

^dIsolated yields of 3 after purification by column chromatography.