| Popis: |
It should be noted that with the Japp--Klingemann reaction hydrazone II is obtained in the syn form, which was confirmed by PMR data in CDCI~ (chemical shift of 7 NH is 12.73 ppm). The syn form of hydrazone II is easily converted to the anti form by dissolving it in DMF, which was also confirmed by PMR spectral data (chemical shift of 7 NH is 9.52 ppm), The displacement of the 7 NH signal of the anti form of II to high field is explained by the rupture of the intramolecular hydrogen 5ond present in the syn form of the hydrazone. |
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