| R |
| |||||
| 4a-d | 5a-d | 6a-d | ||||
|
| Me | CH-N | Me | CH-N | Me | CH-N |
| Phenyl | 7.89 | 2.46 | 2.11 | 8.11 | 1.91 | 8.65 |
| 4-NO2Phenyl | 7.97 | 2.48 | 2.12 | 8.13 | 1.93 | 8.64 |
| 2,4diNO2Phenyl | 8.11 | 2.48 | 2.16 | 8.04 | 1.97 | 8.56 |
| 4-OMePhenyl | 7.85 | 2.45 | 2.09 | 8.01 | 1.89 | 8.64 |