Molecules 2005, 10(7), 809-821; doi:10.3390/10070809
Article

3-Formylchromones IV. The Rearrangement of 3-Formylchromone Enamines as a Simple, Facile Route to Novel Pyrazolo[3,4-b]pyridines and the Synthetic Utility of the Latter

Received: 8 May 2004; in revised form: 4 October 2004 / Accepted: 10 October 2004 / Published: 31 August 2005
This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract: One-pot and facile preparations of 6-(2-hydroxy-5-R-benzoyl)-4-methyl-2-R1- pyrazolo[3,4-b]pyridines 4a-o are described, using the reaction of 3-formyl chromones 1 with 5-amino-1-R1-pyrazoles 2. An enamine-intermediate 2-ethyloxy-6-R-3-(3-methyl-1- phenylpyrazol-5-ylaminomethylene)chroman-4-one 3 was isolated at lower temperatures. Acyloxy-derivatives 5 of compounds 4 were obtained by acylation with acid chlorides or acid anhydrides. Coumarins 6 substituted at the 3- and 4-positions were prepared from the pyrazolo[3,4-b]pyridines 4 by condensation reactions and hydrazones 7 were formed from their reaction with 2,4-dinitrophenyl hydrazine. Reactions under microwave irradiation proceeded significantly faster and with high yields.
Keywords: 4-Oxo-4H[1]benzopyrane; Coumarin; Pyrazole; Rearrangement; Enamine; Microwave irradiation
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MDPI and ACS Style

Lacova, M.; Puchala, A.; Solcanyova, E.; Lac, J.; Kois, P.; Chovancova, J.; Rasala, D. 3-Formylchromones IV. The Rearrangement of 3-Formylchromone Enamines as a Simple, Facile Route to Novel Pyrazolo[3,4-b]pyridines and the Synthetic Utility of the Latter. Molecules 2005, 10, 809-821.

AMA Style

Lacova M, Puchala A, Solcanyova E, Lac J, Kois P, Chovancova J, Rasala D. 3-Formylchromones IV. The Rearrangement of 3-Formylchromone Enamines as a Simple, Facile Route to Novel Pyrazolo[3,4-b]pyridines and the Synthetic Utility of the Latter. Molecules. 2005; 10(7):809-821.

Chicago/Turabian Style

Lacova, M.; Puchala, A.; Solcanyova, E.; Lac, J.; Kois, P.; Chovancova, J.; Rasala, D. 2005. "3-Formylchromones IV. The Rearrangement of 3-Formylchromone Enamines as a Simple, Facile Route to Novel Pyrazolo[3,4-b]pyridines and the Synthetic Utility of the Latter." Molecules 10, no. 7: 809-821.

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