Table 1 Screening of conditions for Birch reductive arylation with fluorobenzene


Entry	Deviations from the standard conditions	Yield of 2a^a
1	None	76% (73%)^b
2	Ball-milling-II for 0 min and PhF was added dropwise to the jar over 5 min	Trace
3	Ball-milling-II for 5 min	18%
4	Li (2.0 eq.) instead of 4.0 eq.	48%
5	Na instead of Li	17%
6	PhCl instead of PhF	0%
7	PhBr instead of PhF	Trace
8	PhOSO₂CF₃ or PhOSO₂Me instead of PhF	0%
9	N, N’-Dimethylethylenediamine (0.35 mL, 3.3 eq.) instead of ethylenediamine	0%
10	TMEDA (0.35 mL, 2.3 eq.) instead of ethylenediamine	11%
11	THF (0.35 mL, 6.0 eq.) instead of ethylenediamine	75% (70%)^b
12	2.5 mmol (0.45 g) scale with a 10-mL stainless-steel jar and two 10-mm balls	43%^b (0.28 g)
13	6.0 mmol (1.1 g) scale with 50-mL stainless-steel jar and two 10-mm balls, 70 °C for ball-milling-II	41% ^b (0.63 g)
14	THF (0.35 mL, 6.0 eq.) instead of ethylenediamine in 6.0 mmol scale with 50-mL stainless-steel jar and two 10-mm balls, 70 °C for ball-milling-II	39% ^b (0.60 g)
15	2.5 mmol (0.45 g) scale with a 10-mL ZrO₂ jar and two 10-mm ZrO₂ balls	42%^b (0.27 g)

Reactions were conducted in a 5.0-mL stainless-steel jar using two 7 mm stainless-steel balls. The reactions were quenched with H₂O after the indicated reaction times.
^a NMR yield using dibromomethane as an internal standard.
^b Isolated yield.

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