1,3-Dipolar cycloaddition of dihydropyran derived nitrones synthesized from 2,3 dihydro 4H-pyran and various hydroxylamines, with electron deficient alkynes are found to have significant rate acceleration and improved yields of isoxazolines in 1-Butyl-3-methylimidazolium based ionic liquids while with enals exclusively endo isoxazolidines are obtained with high selectivity. Synthetic potentiali...

Femtosecond Raman spectroscopy has been developed to investigate ultrafast photoinduced structural changes of materials. Vibrational modes in the photogenerated transient species are measured by stimulated Raman scattering using a Raman pump pulse with narrow bandwidth and a femtosecond supercontinuum probe pulse. The Raman signal can be measured without slowing the temporal response and broade...

A new, simple thermally efficient and solvent-free condensation of 2-amino-3-cyano-6-methyl-4-phenyl-4H-pyran-5-ethylcarboxylate derivatives with coumarin-3-carboxylic acid employing pentafluorophenylammonium triflate (PFPAT) as an inexpensive organocatalyst for the synthesis of a series of ethyl 4,5-dihydro 7-methyl-2-(2-oxo-2H-chromen-3-yl)-4-oxo-5-aryl-3H-chromeno[2,3-d]pyrimidine-6-carboxyl...

The energy relay dye, 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM), was used with a near-infrared sensitizing dye, TT1, to increase the overall power conversion efficiency of a dye-sensitized solar cell (DSC) from 3.5% to 4.5%. The unattached DCM dyes exhibit an average excitation transfer efficiency (ETE) of 96% inside TT1-covered, mesostructured TiO(2) films. Further...

We report an organic solid-state distributed feedback laser consisting of an organic active layer and a Bragg grating without morphological change. The active layer consists of 4-~dicyanomethylene!-2-methyl-6-~4-dimethylaminostryl!-4H-pyran as a laser dye, tris~8hydroxyquinoline! aluminum as a host, and poly~methyl methacrylate! as a binder. The threshold and linewidth of the laser are 400 mJ/c...

The title compound, C(19)H(18)O(7) [systematic name 5-hy-droxy-3,6,7-tri-meth--oxy-2-(4-meth-oxy-phen-yl)-4H-1-benzopyran-4-one], is a flavonoid which was isolated from the traditional Chinese medicine Laggera alata. The benzene ring of the benzopyran-one unit forms dihedral angles of 1.72 (3) and 37.39 (5)° with the pyran ring and the substituent benzene ring, respectively. The mol-ecular conf...

In the title compound, C21H16N2O2, the meth-oxy-benzene ring is almost perpendicular to the mean plane of the naphthalene ring system, making a dihedral angle of 83.62 (5)°. The 4H-pyran ring fused with the naphthalene ring system is almost planar [maximum deviation = 0.033 (1) Å]. In the crystal, mol-ecules are linked into inversion dimers by pairs of N-H⋯N hydrogen bonds. N-H⋯O hydrogen bonds...