TABLE 3.
Optimized conditions for the direct amidation of methyl 4-oxo-4,5-dihydro [1,2,3]triazolo [1,5-a]quinoxaline-3-carboxylate.
| Entry | Amine | Solvent | Catalyst | Temperature/time | Yield |
|---|---|---|---|---|---|
| 1 | Benzylamine (1.3 eq) | Toluene | - | 110°C, 12 h | quantitative |
| 2 | Benzylamine (1.3 eq) | Toluene | Cp2ZrCl2 10% mol | 110°C, 12 h | quantitative |
| 3 | Benzylamine (1.3 eq) | Toluene | CaI2 10% mol | 110 °C, 12 h | quantitative |
| 4 | Benzylamine (2.6 eq) | - | - | rt, 2 h | quantitative |
| 5 | Benzylamine (2.6 eq) | - | - | Ultrasound, 15′ | quantitative |
| 6 | Cyclohexylamine (2.6 eq) | - | - | Ultrasound, 15′ | 97% |
| 7 | Pyrrolidine (2.6 eq) | - | - | Ultrasound, 15′ | 99% |
| 8 | Aniline (2.6 eq) | - | - | Ultrasound, 15′ | Nd |
| 9 | Aniline (1.3 eq) | Toluene (4 M) | CaI2 | 110 °C, 12 h | traces |
| 10 | Aniline (1.3 eq) | Toluene (4 M) | Cp2ZrCl2 10% mol | 110 °C, 12 h | 80% |
| 11 | Aniline (1.3 eq) | CPME | Cp2ZrCl2 10% mol | 110 °C, 12 h | 81% |