An efficient synthesis of pyrazolo[3,4-b]quinolin-5(6H)-one derivatives in ionic liquid

Pyridine-2-carboxylic acid as an effectual catalyst for rapid multi-component synthesis of pyrazolo[3,4-b]quinolinones

Green synthesis of pyrazolo[3,4-b]quinolinones was designed using bioproduct pyridine-2-carboxylic acid (P2CA) as a green and efficient catalyst. The multi-component reaction of aldehydes, 1,3-cyclodiones and 5-amino-1-phenyl-pyrazoles regioselectively produced pyrazolo[3,4-b]quinolinones in excellent yield (84–98%). Recyclization of the catalyst was also investigated. The electronic effect of the various substituents in aromatic rings indicated that the reaction proceeded through the carbocation intermediate. This newly designed protocol very quickly constructed products conventionally under milder conditions.

Green synthesis of pyrazolo[3,4-b]quinolinones was designed using bioproduct pyridine-2-carboxylic acid (P2CA) as a green and efficient catalyst.

Multicomponent Dipolar Cycloaddition Strategy: Combinatorial Synthesis of Novel Spiro-Tethered Pyrazolo[3,4-b]quinoline Hybrid Heterocycles

The stereoselective syntheses of a library of novel spiro-tethered pyrazolo[3,4-b]quinoline-pyrrolidine/pyrrolothiazole/indolizine-oxindole/acenaphthene hybrid heterocycles have been achieved through the 1,3-dipolar cycloaddition of azomethine ylides generated in situ from α-amino acids and 1,2-diketones to dipolarophiles derived from pyrazolo[3,4-b]quinoline derivatives.

l-Proline as an efficient enantioinduction organo-catalyst in the solvent-free synthesis of pyrazolo[3,4-b]quinoline derivatives via one-pot multi-component reaction

The role of l-proline as an efficient organo-catalyst for the three-component synthesis of pyrazoloquinolinones involving dimedone, 3-methyl-1H-pyrazol-5-amine and various aryl aldehydes under mild solvent-free condition is reported.

4-(4-Bromophenyl)-3-methyl-1-phenyl-6,7-dihydro-1H-pyrazolo[3,4-b]thieno[2,3-e]pyridine 5,5-dioxide

In the title compound, C₂₁H₁₆BrN₃O₂S, the pyrazole and pyridine rings are nearly coplanar, the dihedral angle between their planes being 3.17 (14)°. The 2,3-dihydro­thio­phene ring adopts an envelope conformation. The 4-bromo­phen­yl/pyridine ring and phen­yl/pyrazole rings form dihedral angles of 60.06 (9) and 33.49 (11)°, respectively. There is an intra­molecular C—H⋯N hydrogen bond. The crystal packing is stabilized by inter­molecular C—H⋯O hydrogen bonding and C—H⋯π inter­actions.