Optimization of the reaction conditions^a.

Entry	Variation from the standard conditions	Yieldbb (%)
1	None	99
2	Without the ligand	Trace
3	L2 instead of L1	n.r.
4	L3 instead of L1	n.r.
5	L4 instead of L1	73
6	Without LiOtBu	75
7	Air instead of N2	20
8	Commercial CH3CN instead of anhydrous CH3CN	73
9	25 °C instead of 40 °C	96
10	60 °C instead of 40 °C	40

^aReaction was performed with 1a (0.4 mmol, 2 equiv.), NFSI (2, 0.5 mmol, 2.5 equiv.), 3a (0.2 mmol), Cu(CH₃CN)₄PF₆ (0.02 mmol, 10 mol%), ligand (0.024 mmol, 12 mol%) and LiO^tBu (0.2 mmol, 1 equiv.) in anhydrous CH₃CN (2 mL) under a N₂ atmosphere.

^bYield was determined by ¹H NMR with α-methylstyrene as an internal standard. n.r. = no reaction.