Table 1. Optimization of the reaction conditions^a.

Entry	Metal salt	Ligand	Yieldb (%)	erc
1	Mg(OTf)2	L3-PrPr2	23	53.5 : 46.5
2	Co(OTf)2	L3-PrPr2	17	57.5 : 42.5
3	Ni(OTf)2	L3-PrPr2	40	64 : 36
4	Ni(OTf)2	L3-PrEt2	42	64 : 36
5	Ni(OTf)2	L3-RaEt2	41	70.5 : 29.5
6	Ni(OTf)2	L3-PiEt2	32	73.5 : 26.5
7	Ni(OTf)2	L3-PiEt3	27	75.5 : 24.5
8	Ni(OTf)2	L3-PiEt2Ad	23	77 : 23
9d	Ni(OTf)2	L3-PiEt2Ad	26	78 : 22
10d,e	Ni(OTf)2	L3-PiEt2Ad	74	91.5 : 8.5
11d,e,f	Ni(OTf)2	L3-PiEt2Ad	78	96 : 4
12d,e,f,g	Ni(OTf)2	L3-PiEt2Ad	91	95.5 : 4.5

^aUnless otherwise noted, all reactions were carried out with A1 (0.1 mmol), B1 (0.1 mmol), metal/ligand (1/1, 10 mol%), Et₃N (0.1 mmol) in DCM (1.0 mL) at 30 °C for 24 h under N₂ protection. Subsequently, DDQ (0.1 mmol) and CH₂Cl₂ (0.5 mL) were added, and the reaction mixture was stirred at 30 °C for 3 h.

^bIsolated yield.

^cDetermined by HPLC analysis.

^{d i}Pr₂NEt (0.1 mmol).

^eTHF (0.5 mL) at 40 °C.

^fA1 (0.14 mmol), ⁱPr₂NEt (0.14 mmol); EtOAc (1.0 mL) at 10 °C for oxidation.

^gWith 3 μL H₂O.