Table 1.

Optimization studies for copper-catalyzed amination of benz-imidazole (1a) and 2.^[a]

Entry	1a (equiv)	Zn(tmp)2 (equiv)	Copper catalyst	t[a] [h]	Yield [%][b]
1	2.1	1.0	-	24[c]	0
2	2.1	1.0	CuCl	4	88
3	2.1	1.0	CuOTf·tol	4	71
4	2.1	1.0	CuCl2	3.5	89
5	2.1	1.0	Cu(OTf)2	5	76
6	2.1	1.0	Cu(OAc)2	5	99
7	1.4	0.6	Cu(OAc)2	72[c]	56
8	1.05	0.5	Cu(OAc)2	72[c]	40

^[a]Time required for complete consumption of 2 in step 2.

^[b]Yields determined by ¹H NMR spectroscopy with CH₂Br₂ as a quantitative internal standard.

^[c]2 not fully consumed after 72 h. THF = tetra-hydrofuran.