| NMR 1H | Exp | Calc | Exp | Calc | Exp | Calc |
|---|---|---|---|---|---|---|
| 4a | 6a | 9a | ||||
| N–OH | 12.8 (br. s) | 10.2 | — | — | — | — |
| H-2′; H-6′ | 8.3 (s)b | 7.5 | 8.3 (d, J = 8.7 Hz) | 7.7 | 8.2 (d, J = 8.9 Hz) | 7.4 |
| H-3′; H-5′ | 8.4 (d, J = 8.7 Hz) | 7.4 | 8.4 (d, J = 8.9 Hz) | |||
| OCH3/NCH3 | — | — | 4.1 (s) | 3.7 | 3.6 (s) | 3.0 |
| –COCH2– | 2.4(s) | 2.0 | 2.5 (s) | 1.9 | 2.4 (s) | 1.8 |
| 2CH3 | 1.1 (s) | 0.7 | 1.1 (s) | 0.7 | 1.1 (s) | 0.7 |
| –CH2– | 2.7 | 2.2 | 2.7 (s) | 2.3 | 2.9 (s) | 2.3 |
a
For the convenience, the numeration of the atoms in N-oxide cycle is the same as in N-methoxy- and N-hydroxy derivatives.
b
In this case the signals of aromatic protons are a singlet.