Para toluenesulfonic acid-catalyzed one-pot, three-component synthesis of benzo[5,6]chromeno[3,2-c]quinoline compounds in aqueous medium

A new series of benzo[5,6]chromeno[3,2-c]quinoline derivatives were successfully synthesized using various arylglyoxal monohydrates, quinoline-2,4-dione, and β-naphthol in H2O:EtOH (2:1) as a green solvent in the presence of catalytic amounts p-toluenesulfonic acid as a mild catalyst under reflux conditions with high yields (83–92%). The reaction conditions were optimized in different solvents at variable thermal conditions, and the optimized reaction condition for this synthesis has been reported. The structures of all new products were defined by 1H-NMR, 13C-NMR, FT-IR, mass spectral data, and HRMS.

Fast and Efficient Green Procedure for the Synthesis of Benzo[5,6]chromene Derivatives and Their Sulfur Analogues in Water by Organocatalyst Potassium Phthalimide-N-oxyl

A simple, clean, straightforward, and environmentally benign one-pot, three-component reaction of various arylglyoxal monohydrates, β-naphthol, and barbituric acid [pyrimidine-2,4,6(1H,3H,5H)-trione] or thiobarbituric acid in the presence of catalytic amounts potassium phthalimide-N-oxyl (PPINO), as a mild and efficient organocatalyst in aqueous media under reflux conditions is reported. This transformation produced the novel diverse-substituted 12-benzoyl-8,12-dihydro-9H-benzo[5,6]chromeno[2,3-d]pyrimidine-9,11(10H)-diones and their sulfur analogues in 82–93% yield via filtration and without utilization of any chromatography. The high yields of products, very simple operation, easy workup, availability of starting materials, green process, and high atom-economy are the main benefits of this synthetic strategy.

1,4-Diazabicyclo[2.2.2]octane-Catalyzed Multicomponent Domino Strategy for the Synthesis of Tetrasubstituted NH-Pyrroles

A mild and efficient 1,4-diazabicyclo[2.2.2]octane (DABCO)-catalyzed three-component domino reaction was developed for the synthesis of highly functionalized NH-pyrroles from arylglyoxal monohydrates, enamino esters, and cyclic 1,3-dicarbonyl compounds in 1,4-dioxane at room temperature for 0.5 hours. Various substituted NH-pyrroles were obtained in moderate to good yields.

Base-Promoted Tandem Cyclization for the Synthesis of Polyfunctional 2-Hydroxy-2,3-dihydrofurans from Arylglyoxal Monohydrates and 3-(1H-Indol-3-yl)-3-oxopropanenitrile

An efficient base-promoted tandem cyclization for the synthesis of polyfunctional 2-hydroxy-2,3-dihydrofurans from arylglyoxal monohydrates and 3-(1H-indol-3-yl)-3-oxopropanenitrile has been established. The investigation of the mechanism suggested that this reaction proceeds through a Knoevenagel condensation–Michael addition–oxidation–cyclization sequence. This method demonstrates the compatibility with a wide range of functional groups to produce the 2-hydroxy-2,3-dihydrofuran scaffolds in good to excellent yields in one pot.

Two Efficient One-Pot Approaches for Regioselective Synthesis of New 3-Arylpyridazino[4,3-c]quinolin-5(6H)-ones

Two efficient regioselective approaches for the one-pot synthesis of 3-arylpyridazino[4,3-c]quinolin-5(6H)-one derivatives are reported, by the three-component reaction of arylglyoxal monohydrates, quinoline-2,4-diol, and hydrazinium dihydrochloride or hydrazine hydrate in ethanol and pyridine. In ethanol, the reactions were catalyzed by 1,4-diazobicyclo[2,2,2]octane. The features of both procedures are high regioselectivity, mild reaction conditions, good to high yields, and operational simplicity.