Table 1 Comparative performances of the Talc catalyst for the synthesis of Pyranopyrazoles under different conditions.
Entry | Solvent/catalyst (g) | Condition | Time (min) | Yield (%)a |
|---|---|---|---|---|
1 | –/– | R.T. | 120 | Trace |
2 | H2O/– | R.T. | 120 | Trace |
3 | C2H5OH/– | R.T. | 120 | Trace |
4 | C2H5OH/– | Reflux | 90 | 17 |
5 | H2O/– | Reflux | 90 | 5 |
6 | C2H5OH/Talc (0.01) | Reflux | 80 | 43 |
7 | C2H5OH/Talc (0.02) | Reflux | 80 | 51 |
8 | C2H5OH/Talc (0.04) | Reflux | 60 | 66 |
9 | C2H5OH: H2O /Talc (0.04) | Reflux | 60 | 44 |
10 | –/Talc (0.04) | R.T. | 60 | 71 |
11 | –/Talc (0.04) | Mixer Mil 20 Hz | 5 | 97 |
12 | –/– | Mixer Mil 20 Hz | 20 | 19 |
13 | –/Talc (0.04) | Mixer Mil 15 Hz | 15 | 71 |
14 | –/Talc (0.04) | Mixer Mil 10 Hz | 30 | 52 |
15 | –/NaOH (0.04) | Mixer Mil 20 Hz | 10 | 95b |
16 | –/K2CO3 (0.04) | Mixer Mil 20 Hz | 15 | 90b |
17 | –/MgO (0.04) | Mixer Mil 20 Hz | 10 | 95b |
18 | –/Hydrotalcite (0.04) | Mixer Mil 20 Hz | 18 | 98b |
