Comparison of the reaction conditions and results for the synthesis of xanthene 3aa.
| Entry | Catalyst | Condition | Time | Yield 3a (%) | Ref. |
|---|---|---|---|---|---|
| 1 | Fe+3-montmorillonite (15 wt%) | 100 °C/EtOH | 6 h | 97 | 87 |
| 2 | Alumina-sulfuric acid (200 mg) | Reflux/EtOH | 4 h | 83 | 88 |
| 3 | SBSANb (0.5 g) | 50 °C/solvent-free | 2 h | 95 | 89 |
| 4 | PANI-PTSAc (25 wt%) | Reflux/H2O | 6 h | 75 | 90 |
| 5 | SBSSAd (0.1 g) | Reflux/EtOH | 10 h | 98 | 91 |
| 6 | Nano ZnAl2O4 (90 mg) | Reflux/EtOH | 15 min | 88–98 | 92 |
| 7 | ICl3/SiO2 (5 mol%) | 75 °C/solvent free | 1 h | 90 | 28 |
| 8 | In(CF3SO3)3 (2 mol%) | 100 °C/solvent free | 1 h | 95 | 28 |
| 9 | LUS-Pr-SO3He (0.02 g) | 140 °C/solvent free | 15 min | 90 | 93 |
| 10 | [cmmim][BF4] (0.2 g) | 80 °C/solvent free, MW | 2 h | 94 | 94 |
| 11 | NP (1.5 g) | Reflux/EtOH | 6.5 h | 90 | 78 |
| 12 | Cu(ii)/NP (0.2 g) | Reflux/EtOH | 2 h | 98 | This study |
a
Reaction conditions: dimedone (2 mmol), 4-chlorobenzaldehyde (1 mmol), catalyst.
b
Silica boron-sulfuric acid nano particles (SBSAN).
c
Nano ferrite-glutathione-copper (PANI-PTSA).
d
Silica bonded S-sulfonic acid (SBSSA).
e
Propyl sulfonic acid functionalized LUS-1 (Laval University silica) (LUS-Pr-SO3H).