Table 4 The reaction of 4-nitrobenzaldehyde (1 mmol), ethyl acetoacetate (1 mmol) and 2-aminobenzothiazole (1 mmol) under various conditions.
|
Entry | Solvent | Conditions (°C) | Catalyst | Amount of Catalyst (g) | Time (min) | Yield (%)a |
|---|---|---|---|---|---|---|
1 | H2O | Reflux | Bentonite/Ti(IV) | 0.06 | 200 | 45 |
2 | EtOH | Reflux | Bentonite/Ti(IV) | 0.06 | 240 | 55 |
3 | H2O/EtOH (1:1) | Reflux | Bentonite/Ti(IV) | 0.06 | 180 | 50 |
4 | Solvent-free | r.t | Bentonite/Ti(IV) | 0.06 | 360 | – |
5 | Solvent-free | 70 | Bentonite/Ti(IV) | 0.06 | 180 | 80 |
6 | Solvent-free | 80 | Bentonite/Ti(IV) | 0.06 | 150 | 71 |
7 | Solvent-free | 90 | Bentonite/Ti(IV) | 0.06 | 120 | 87 |
8 | Solvent-free | EMHb/85 | Bentonite/Ti(IV) | 0.06 | 45 | 96 |
9 | Solvent-free | EMHb/85 | Bentonite/Ti(IV) | 0.05 | 120 | 75 |
10 | Solvent-free | EMHb/85 | Bentonite/Ti(IV) | 0.04 | 180 | 60 |
11 | Solvent-free | EMHb/85 | Bentonite/Ti(IV) | 0.07 | 40 | 73 |
12 | Solvent-free | EMHb/85 | Bentonite | 0.06 | 45 | 30 |
