نتایج جستجو برای: 2h pyrans
تعداد نتایج: 11400 فیلتر نتایج به سال:
A procedure has been developed for synthesis of 2-alkenyl-2H-indazoles starting from 2-(2-carbonylmethyl)-2H-indazoles, which are prepared by gallium/aluminium- and aluminium-mediated, direct, regioselective alkylation of indazoles with α-bromocarbonyl compounds. The structure of 3-(2H-indazol-2-yl)-2H-chromen-2-one was proven by X-ray crystallography. The styrene- and coumarin-2H-indazoles pro...
We report a detailed study of electrical and thermal transport properties in 2H-M$_x$TaS$_2$ (M = Mn, Co) magnets where M atoms are intercalated the van der Waals gap. The intercalation induces ferromagentism with an easy-plane anisotropy 2H-Mn$_x$TaS$_2$, but ferromagnetism strong uniaxial 2H-Co$_{0.22}$TaS$_2$, which finally evolves into three-dimensional antiferromagnetism 2H-Co$_{0.34}$TaS$...
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...
In the structure of the title compound, C12H12O3, the di-hydro-pyran ring is fused with the benzene ring. The di-hydro-pyran ring is in a half-chair conformation, with the ring O and methyl-ene C atoms positioned 1.367 (3) and 1.504 (4) Å, respectively, on either side of the mean plane formed by the other four atoms. The meth-oxy group is coplanar with the benzene ring to which it is connected ...
In the title compound, C20H17N3O4, the central pyran ring adopts a boat conformation with the O atom and diagonally opposite C atoms displaced by 0.1171 (1) and 0.1791 (1) Å, respectively, from the mean plane defined by the other four atoms. The coplanar atoms of the pyran ring and the meth-oxy-benzene ring are nearly perpendicular, as evidenced by the dihedral angle 87.01 (1)°. The amine H ato...
In the title compound, C(34)H(38)O(6), the methyl groups on each pyran ring exhibit 1,3-cis stereochemistry, established during synthesis by pseudo-axial delivery of hydride during a lactol reduction step. In the crystal structure, the mol-ecule lies on a twofold rotation axis and the torsion angle about the central diaryl bond is 41.3 (1)°. The mol-ecules pack in a herringbone arrangement.
In the title compound, C(31)H(38)O(17), the 1,3-dioxane and pyran-oside rings both show (4)C(1) chair conformations while for the d-fructofuran-oside moiety an envelop 3E conformation is observed. The phenyl ring is oriented almost perpendicular to the 1,3-dioxane ring [dihedral angle = 79.3 (2)°], and the acetate groups are equatorial for the pyran-oside ring and axial for the furan-oside ring...
In the title compound, C(21)H(19)ClO(3), the two cyclo-hexenone rings adopt half-chair conformations, whereas the pyran ring adopts a boat conformation. The 4-chloro-phenyl ring is almost perpendicular to the plane through the four C atoms of the pyran ring [dihedral angle = 87.97 (6)°]. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into a chain parallel to the a-axis.
A viable route has been developed for the selective synthesis of the 4→6-linked catechin dimers, scarcely accessible from Nature and/or through synthesis. An acyclic nucleophilic catechin precursor (seco-catechin) was used for the regioselective union with an electrophilic catechin unit, and subsequent pyran cyclization gave the desired 4→6-linked dimers, i.e., procyanidin B6 and catechin-(4α→6...
The purpose of the present article is to show the multilinearity for symbols in Goodwillie-Lichtenbaum motivic complex in two cases. The first case shown is where the degree is equal to the weight. In this case, the motivic cohomology groups of a field are isomorphic to the Milnor’s K-groups as shown by Nesterenko-Suslin, Totaro and Suslin-Voevodsky for various motivic complexes, but we give an...
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