Table 2.
Q-Tube method in the intramolecular Friedel-Craft acylation of 3-(4-methoxyphenyl) propionic acid 1.
| Entry | Catalyst (%mol) | Solvent | T (°C) | Time (min) | Conv. (%) | Yield (%) a |
|---|---|---|---|---|---|---|
| 1 | TfOH (3 eq.) | CH2Cl2 (dry) | 80 | 60 | 100 | 100 |
| 2 | TfOH (3 eq.) | CH2Cl2(dry) | 110 | 30 | 100 | 96 |
| 3 | TfOH (3 eq.) | CH2Cl2(dry) | 150 | 10 | 100 | trace b |
| 4 | Tb(OTf)3 (10) | C6H5Cl | 180 | 180 | 100 | 40 |
| 5 | Tb(OTf)3 (10) | toluene | 150 | 180 | 100 | 86 c |
| 6 | Tb(OTf)3 (10) | n-C7H14 | 180 | 240 | - | - |
| 7 | Tb(OTf)3 (20) | n-C7H14 | 250 | 120 | 18 | 45 |
| 8 | Tb(OTf)3 (10) | isooctane | 250 | 240 | 32 | 20 |
| 9 | TfOH-SiO2(30 ) | CH2Cl2 (dry) | 25 | 120 | - | - |
| 10 | TfOH-SiO2 (30) | CH2Cl2 (dry) | 180 | 180 | - | - |
a Isolated yields; b The high temperature broke the Teflon septum; c Formation of intermolecular Friedel-craft acylation by-products.