Table 1. Mechanistic Study and Optimization of the Ar–Cl Cross-Ullman Reaction.

entry	change from the optimized conditionsc	3a (%)d
1	none	84
2	NaCl instead of LiCl	62
3	LiBr instead of LiCl	59
4	Bu4NCl instead of LiCl	53
5	TMSCl instead of LiCl	16
6	no LiCl	<10
7	Mn instead of Zn	62
8	Mn instead of Zn, LiBr instead of LiCl	77
9	without PdCl2 and dppb	44
10	without NiCl2(dme) and dtbbpy	<5
11	reaction set up on the benchtope	80
12	1.2 equiv of 2a	90 (89f)

^aIn DMF. See the Supporting Information for details on electrochemical studies.

^bReduction of III was conducted in DMF at a concentration of 0.025 M with Zn powder (40 equiv). Cyclooctadiene (0.125 M) was added to stabilize the product. Salts (1–40 equiv) were added in some cases. See the Supporting Information for additional results and experimental details.

^cReactions were run on a 0.5 mmol scale in 2 mL of solvent. NMP = N-methyl-2-pyrrolidinone.

^dGC yield vs dodecane as an internal standard.

^eThe reaction was set up under air with dry solvent.

^fIsolated yield.