This work provides a novel approach for the instant detection of CN− anions based on chromogenic 6-[(E)-(4-nitrophenyl)diazenyl]-1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indole] derivatives. New colorimetric detectors were synthesized and characterized. These compounds exhibited substantial color change from orange to magenta blue when treated with cyanide ions in CH3CN solution buffered sodium ...

From the methanol extract of the aerial parts of Peperomia blanda (Piperaceae), two chromenes were isolated and characterized mainly through application of 2D-NMR spectroscopy. The structures were 2S-(4-methyl-3-pentenyl)-6-formyl-8-hydroxy-2,7-dimethyl-2H-chromene and 2S-(4-methyl-3-pentenyl)-5-hydroxy-6-formyl-2,7-dimethyl-2H-chromene named as blandachromenes I and II, respectively.

Four N-(4-halophen-yl)-4-oxo-4H-chromene-3-carboxamides (halo = F, Cl, Br and I), N-(4-fluoro-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10FNO3, N-(4-chloro-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10ClNO3, N-(4-bromo-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10BrNO3, N-(4-iodo-phen-yl)-4-oxo-4H-chromene-3-carboxamide, C16H10INO3, have been structurally characterized. The mol-ecules...

A novel cinchona-alkaloid-derived organocatalyst has been developed to catalyze the asymmetric regioselective [3+2] cycloaddition of 3-isothiocyanato oxindoles with dibenzylidene ketones. A series of spirooxindole enols could be obtained in high yields with good-to-excellent diastereo- and enantioselectivities.

The first chiral phosphoric acid catalyzed highly diastereo- and enantioselective 1,3-dipolar cycloaddition reaction of azlactones and methyleneindolinones was disclosed. By using a BINOL-derived chiral phosphoric acid as the catalyst, azlactones were activated as chiral anti N-protonated 1,3-dipoles to react with methyleneindolinones to yield biologically important 3,3'-pyrrolidonyl spirooxind...

A highly enantioselective organocatalytic vinylogous aldol-cyclization cascade reaction of 3-alkylidene oxindoles to isatins has been achieved by using bifunctional organocatalysts. The unexpected intramolecular lactonization which follows the initial aldol reaction, leading to the cleavage of the oxindole ring and generation of enantioenriched spirooxindole dihydropyranones in good to excellen...

In the title compound, C(16)H(9)BrO(5)·2C(3)H(7)NO, the chromene ring system is essentially planar. The two dimethyl-formamide solvent mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds to the 6-bromo-3-hydr-oxy-4-oxo-2-phenyl-4H-chromene-8-carboxylic acid molecules.