Table 1. C–H Arylation Catalyst Optimizationa.
| entry | catalyst | 3ab (%) |
|---|---|---|
| 1 | [Ru(p-cymene)Cl2]2 (4 mol %) | nd |
| 2 | NiBr2·diglme/dtbbpy (4 mol %) | nd |
| 3 | [Ru(p-cymene)Cl2]2 (4 mol %) and NiBr2·diglme/dtbbpy (4 mol %) | 45 |
| 4 | [Ru(p-cymene)Cl2]2 (4 mol %) and dtbbpy (4 mol %) | 48 |
| 5 | [Ru(p-cymene)Cl2]2 (4 mol %) and PCy3 (8 mol %) | 91 (94c) |
| 6 | RuCl3·3H2O (8 mol %) and PCy3 (8 mol %) | 68 |
Reactions run with 2-methylbenzoic acid 1a (0.25 mmol) and 2a (1.5 equiv).
GC yield of methyl ester, uncorrected.
Isolated yield of methyl ester. Dtbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine.
