- Journal
- MONATSHEFTE FUR CHEMIE
- Année
- 2016
- Volume
- 147
- Numéro
- 6
- Pages
- 1069-1079
- Mois
- JUN
- DOI
- 10.1007/s00706-016-1660-7
Abstract
The condensation of hydrazine, N-methylhydrazine, and N-phenylhydrazine with ethyl 4-chloro-2-oxo-1,2-dihydroquinoline-3-carboxylate derivatives has been investigated. As a result, 12 new antioxidant pyrazolo[4,3-c]quinolin-3,4-diones were obtained with good to high yields. When two cross-products could be possible, only one isomer bearing the methyl or the phenyl group at the N1 position is isolated and unequivocally characterized using 1D and 2D NMR techniques, FT-IR, and combustion analyses. DFT analysis of the reaction mechanism was carried out in the Pearson's hard soft acid base framework, confirming the assigned structure to the observed pyrazolo[4,3-c]quinolin-3,4-diones. These calculations indicate a favored kinetic control for the synthesized pyrazolo[4,3-c]quinolin-3,4-diones compared to its possible regioisomer.