Silica tungstic acid (STA) has been found to be an efficient and reusable solid acid catalyst for the synthesis of 2-amino-4H-chromenes via the three-component reaction of aromatic aldehydes, malononitrile, and β-naphthol. STA as a novel solid acid was characterized by X-ray fluorescence, X-ray diffraction, and Fourier transform infrared spectroscopy.

ABSTRACT A series of 6'-chloro-1',1'-dioxospiro[4H-benzo[d][1,3,7]oxadiazocine-4,3'(2'H)-[1,4,2]benzodithiazine]-2,6(1H,5H)dione derivatives have been synthesized from isatoic anhydride and 3-(R2-amino)-1,4,2-benzodithiazine 1,1-dioxides. Some synthetic limitations are discussed on the basis of quantum chemical calculations performed by use of the Hartree-Fock method. GRAPHICAL ABSTRACT

A series of 2-amino-4H-pyran-3-carbonitrile derivatives were designed and synthesized. Their antitubercular activities were evaluated against autoluminescent M. tuberculosis H37Ra and standard strain M. tuberculosis H37Rv. No obvious antitubercular activities could be observed (MIC > 10 g/mL). The results are in sharp contrast with the previously reported data.

The water-coordinated Er(III) atom in the title compound, [Er(C(5)H(4)N(3)O(2))(3)(H(2)O)(2)]·4H(2)O, is N,O-chelated by three 3-amino-pyrazine-2-carboxyl-ate ions and has a square-anti-prismatic geometry. The mononuclear mol-ecule inter-acts with the solvent water mol-ecules to generate a three-dimensional hydrogen-bonded network.

A one-pot three-component condensation of an aldehyde, malononitrile, and resorcinol has been achieved by ultrasound method. The reaction has been catalyzed by glycine in aqueous medium. This protocol afforded corresponding 2-amino-4H-chromenes in shorter reaction times, high yields and simple work-up procedures with the green aspects by avoiding toxic reagents.

An operationally simple and efficient protocol for the construction of dihydrofuran derivatives has been accomplished via a sequential addition of N-chlorosuccinimide and a base to 2-amino-4H-pyran derivatives in alcohol medium. The one-pot protocol proceeding via tandem oxidative difunctionalization and ring contraction provides an entirely new strategy for the construction of the dihydrofuran...

Alum (KAl(SO4)2 · 12H2O) is an inexpensive, efficient, and nontoxic catalyst used for the synthesis of 2-[3-amino-5-methyl-5-(pyridin-3-yl)-1,5-dihydro-4H-1,2,4-triazol-4-yl]propanoic acid derivatives in aqueous media by the reaction of 3-acetyl pyridine (1), amino acids (2)/(6), and thiosemicarbazide (4) at 80 °C. This methodology offers significant improvements for the synthesis of products w...

A novel Schiff base (Z)-4-(((2-hydroxy phenyl)amino)(phenyl)methylene)-3-methyl-1-phenyl-1Hpyrazol-5(4H)-one and its analogues were synthesized by condensation of 5-methyl-2-phenyl-4-substituted pyrazolin3-one with 2-amino phenol from alcoholic solution.Schiff base ligands arecharacterizedby IR, UV, NMR, elemental analysis and single crystal Xray diffraction analysis. These potential ligands ar...