Table 1 Optimization of reaction conditions^a


Entry	Deviation from standard conditions	Yield of 3 (%)^b
1	none	86
2	THF as solvent	41
3	MeCN as solvent	70
4	DME as solvent	78
5	Mn instead of Zn	9
6	without DMAP	76
7	without Cy₂NH	8
8	without NiCl₂^.dtbbpy	n.d.
9	without ClPPh₂ or Zn or I₂	n.d.
10	under air	4

^aStandard reaction conditions: 1a (0.1 mmol, 1.0 equiv.), 2a (0.2 mmol, 2.0 equiv.), NiCl₂^.dtbbpy (0.01 mmol, 10 mol%), ClPPh₂ (0.11 mmol, 1.1 equiv.), DMAP (0.01 mmol, 10 mol%), and Cy₂NH (0.12 mmol, 1.2 equiv.) in 1,4-dioxane (0.25 mL, 0.4 M) at room temperature for 20 min; then Zn (0.3 mmol, 3.0 equiv.), I₂ (0.1 mmol, 1.0 equiv.) at room temperature for 18 h. ^bIsolated yield. n.d. not detected. See Supplementary Section 3 for more details on optimization studies and control experiments.

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