Table 2.
The synthesis of multisubstitued [1,2,4]-triazolo[4,3-a] pyrimidines under heating and ultrasonic irradiation.
| Entry | Ar | Product | Method A a | Method B b | |
|---|---|---|---|---|---|
| Time(min)/Yields (%) c | Time(min)/Yields (%) c | ||||
| 1 | 4-Me-C6H4 | 4a | 30/70 | 60/75 | |
| 2 | 4-MeO-C6H4 | 4b | 30/74 | 60/80 | |
| 3 | 3,4-2MeO-C6H4 | 4c | 30/78 | 60/84 | |
| 4 | 3-HO-C6H4 | 4d | 30/78 | 60/84 | |
| 5 | 4-F-C6H4 | 4e | 30/80 | 60/86 | |
| 6 | 4-Br-C6H4 | 4f | 30/85 | 60/90 | |
| 7 | 2-Cl-C6H4 | 4g | 30/70 | 60/75 | |
| 8 | 4-Cl-C6H4 | 4h | 30/82 | 60/88 | |
| 9 | 2,4-2Cl-C6H4 | 4i | 30/78 | 60/83 | |
| 10 | 4-O2N-C6H4 | 4j | 30/60 | 60/67 | |
| 11 | 4-Me2N-C6H4 | 4k | 30/79 | 60/84 | |
| 12 | 3-Pyridyl | 4l | 30/75 | 60/80 | |
| 13 | 4-Pyridyl | 4m | 30/68 | 60/75 |
a Reaction under reflux conditions; b Reaction under ultrasonic waves at 25~30 °C and ultrasonic power 250 W, irradiation frequency 25 Khz; c Isolated yields.