Table 4. Data from the Separation of the Racemic HBNGs by HPLC.
| ORa [α]D20 | 102 × gabs | HPLC ee (%) | |
|---|---|---|---|
| (+)-[9]HBNG | +6706 | +3.6 | 98 |
| (−)-[9]HBNG | –7120 | –2.8 | 99 |
| (+)-[10]HBNG | +2447 | +1.4b | 73 |
| (−)-[10]HBNG | –4480 | –1.6 | 99 |
| (+)-[11]HBNG | +4033 | +1.0 | 99 |
| (−)-[11]HBNG | –4270 | –1.0 | 99 |
a
Optical rotation in THF. In addition to the loss of the material during chromatography, especially in the case of [10]HBNG, there were residual solvents present in the resolved samples, mainly toluene and/or dichloromethane (Section 9, see the Supporting Information). The larger discrepancy in the absolute values of the optical rotations of the opposite enantiomers is due to the presence of residual solvents after HPLC separation, see the Supporting Information for details.
b
Corrected to optical purity (i.e., scaled by a factor of ∼1.4).