Table 4.

Direct arylation of 2-phenylpyridine with (hetero)aryl chlorides catalyzed by ruthenium(II)-NHC complexes 2a–e ^a.

Entry	Ru-NHC	(Het)ArCl	Time (h)	Conversion (%)	Yield (%)
					A	B
1	2a		1	100	100	-
2	2b		1	100	100	-
3	2c		1	80	80	20
4	2d		1	90	90	10
5	2e		1	85	87	13
6	2a		5	100	100	-
7	2b		5	100	100	-
8	2c		5	100	100	-
9	2d		5	100	88	12
10	2e		5	90	95	5
11	2a		5	100	70	30
12	2b		5	100	80	20
13	2c		5	100	72	28
14	2d		5	100	92	8
15	2e		5	100	86	14
16	2a		5	76	76	24
17	2b		5	72	72	28
18	2c		5	71	71	29
19	2d		5	70	70	30
20	2e		5	80	85	15
21	2a		5	72	72	28
22	2b		5	77	77	23
23	2c		5	70	70	30
24	2d		5	79	79	21
25	2e		5	74	75	25
26	2a		5	76	76	24
27	2b		5	71	71	29
28	2c		5	88	88	22
29	2d		5	85	85	15
30	2e		5	89	90	10
31	2a		20	90	90	10
32	2b		20	88	95	5
33	2c		20	95	100	-
34	2d		20	89	97	3
35	2e		20	83	85	15

^a Reaction conditions: KOAc (0.05 mmol), ruthenium(II)-NHC complexes 2a–e (0.025 mmol), H₂O as solvent (2 mL), r.t. for 1 h, then 2-phenylpyridine (0.5 mmol), (Het)ArCl (1.25 mmol), Cs₂CO₃ (1.5 mmol).