Table 1. Optimization of Reaction Conditionsa.

| entry | catalyst | additive | solvent | temp (°C) | yield (%)b |
|---|---|---|---|---|---|
| 1 | Rh(PPh3)3Cl | AgNTf2 | DCE | reflux | trace |
| 2 | Rh2(OAc)4 | AgNTf2 | DCE | reflux | trace |
| 3 | [Cp*Co(CO)I2] | AgNTf2 | DCE | reflux | trace |
| 4 | [Cp*RhCl2]2 | AgNTf2 | DCE | reflux | 81 |
| 5 | AgNTf2 | DCE | reflux | trace | |
| 6 | [Cp*RhCl2]2 | AgNTf2 | MeOH | reflux | 31 |
| 7 | [Cp*RhCl2]2 | AgNTf2 | EtOH | reflux | 35 |
| 8 | [Cp*RhCl2]2 | AgNTf2 | toluene | 100 | 56 |
| 9 | [Cp*RhCl2]2 | AgNTf2 | DCM | reflux | 51 |
| 10 | [Cp*RhCl2]2 | AgNTf2 | TFEA | reflux | 28 |
| 11c | [Cp*RhCl2]2 | AgNTf2 | DCE | reflux | 49 |
| 12d | [Cp*RhCl2]2 | AgNTf2 | DCE | reflux | 75 |
| 13e | [Cp*RhCl2]2 | AgNTf2 | DCE | reflux | 46 |
| 14f | [Cp*RhCl2]2 | AgNTf2 | DCE | reflux | 78 |
| 15 | [Cp*RhCl2]2 | AgNTf2 | DCE | rt | trace |
| 16 | [Cp*RhCl2]2 | AgNTf2 | DCE | 40 | 18 |
| 17 | [Cp*RhCl2]2 | AgNTf2 | DCE | 60 | 32 |
| 18 | [Cp*RhCl2]2 | AgNTf2 | DCE | 80 | 65 |
Reaction conditions: 2-diazo-5,5-dimethylcyclohexane-1,3-dione 1e (0.5 mmol), acetanilide 2a (0.5 mmol), solvent (3 mL), and catalyst (1.0 mol %) for 12 h.
Isolated yields.
5 mol % of additive was used.
20 mol % of additive was used.
0.5 mol % of catalyst was used.
2 mol % of catalyst was used.