Table 3.

Screening of the reaction conditions using iodide salts^[a]

Entry	Iodide salts	Equiv	Solvent	Yield of4 a[%][b]	Yield of6 a[%][b]
1	TBAI	1.0	DMF	21[c]	0
2	TBAI	1.0	MeCN	19[d]	trace
3	TBAI	1.0	MeOH	16[e]	3
4	TBAI	1.0	1,4-dioxane	37[f]	0
5[g,h,i]	TBAI	0.3	1,4-dioxane	78[e,j]	0
6	I2	1.0	1,4-dioxane	0	3
7	NaI	1.0	1,4-dioxane	trace	50
8	KI	1.0	1,4-dioxane	trace	61
9	CsI	1.0	1,4-dioxane	trace	72
10	KI	1.0	DMF	22[c]	0
11	CsI	1.0	DMF	30[k]	0
12[g]	CsI	1.1	1,4-dioxane	0	88
13[g,l]	KI	1.1	1,4-dioxane	0	92[j]

[a] The reactions were carried out with Togni reagent 1 (1.2 equiv) and additive on a 0.25 mmol scale, unless otherwise noted. [b] Determined by ¹⁹F NMR analysis using fluorobenzene as an internal standard. [c] The E/Z ratio was 6:1. [d] The E/Z ratio was 17:2. [e] The E/Z ratio was 7:1. [f] The E/Z ratio was 8:1. [g] Run with 1.5 equiv of Togni reagent 1. [h] Run for 12 h. [i] Run in 0.5 m solution. [j] Yield of isolated product. [k] The E/Z ratio was 13:2. [l] Run at 60 °C for 9 h.