نتایج جستجو برای: eight membered rings
تعداد نتایج: 228395 فیلتر نتایج به سال:
The title compound, C16H24Br2O, was synthesized from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzocyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus atlantica). The mol-ecule contains fused six- and seven-membered rings, each linked to a three-membered ring. The six-membered ring has a half-chair conformation, while the seven-membered rin...
Herein we report the synthesis, structure solution, and catalytic properties of PST-31, which has an unprecedented framework topology. This high-silica (Si/Al=16) zeolite was synthesized using a pyrazolium-based dication with tetramethylene linker as organic structure-directing agent (OSDA) in hydroxide media. The PST-31 is built from new building layers containing four-, five-, six-, seven-mem...
The “diverted Heck” reaction has been shown to be a potent method synthesize cyclopropanes from electron-rich olefins and iodomethyl trifluoroborate. Nevertheless, it is not mechanistically limited the three-membered rings. synthesis of five-membered rings using bifunctional substrates with halide moiety an organometallic group described. Furthermore, reactions respective boron tin-based are fu...
The title compound, C28H24O5, consists of a fused tricyclic system containing two five-membered rings and one six-membered ring. The five-membered rings both exhibit an envelope conformation with the O atom at the flap, whereas the six-membered ring adopts a boat conformation. The dihedral angle between the 4-methyl-phenyl rings at the 1,8-positions is 76.4 (1)°. In the crystal, mol-ecules are ...
The title compound, C16H25Cl2N, was synthesized from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzocyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule is built up from fused six- and seven-membered rings linked to two three-membered rings. The six-membered ring shows a half-chair conformation, whereas the seven-mem...
In the quaternary system Cs / Nd / Si / O, two new representatives, the phyllo-oxosilicate Cs3NdSi8O19 and the tecto-oxosilicate Cs6Nd2Si21O48, were synthesized by CsF-flux-supported solid-state reactions between Nd2O3 and SiO2. The first one, Cs3NdSi8O19 (orthorhombic, Cmcm (no. 63), a = 705.74(5), b = 2712.85(19), c = 1163.72(8) pm, Z = 4), is not isotypic to the related scandium compound Cs3...
Here we explore in silico an alternative to make planar eight π-electron bare ring systems with substitutions of some cyclooctatetraene ring carbon atoms by heavier group 14 elements. We found that the most stable eight membered rings with formulae C(4)Si(4)H(8), C(4)Ge(4)H(8), and C(4)Sn(4)H(8) have a perfect planar structure, enhancing delocalization energy as compared to cot.
THE TITLE COMPOUND [SYSTEMATIC NAME: (1S,4S,5R,7S,8S,9R,10R,11S,13S,14S,16S,17R)-N-methyl-8,14-dihy-droxy-1,16-tri-meth-oxy-4-(meth-oxy-methyl-ene)aconitane], C(24)H(39)NO(5), was isolated from the roots of Aconitum carmichaelii Debx., which is known as 'Chuanwu' in Chinese traditional herbal medicine. The mol-ecule has an aconitane carbon skeleton with four six-membered rings and two five-memb...
There are two independent mol-ecules in the asymmetric unit of the title compound, C(30)H(44)O(5). They comprise a triterpenoid skeleton of five six-membered rings and a five-membered lactone ring. The five six-membered rings are all trans-fused. In both independent mol-ecules the D rings adopt a slightly distorted half-chair conformation due the presence of the lactone ring while the other fou...
Conformational properties of N-aryl-1-azacyclooctan-5- ones with a p-methyl, m-methyl, and p-methoxy group as a substituent have been studied by 1H-NMR, 13C-NMR and IR spectroscopies. Transannular interaction of the two functional groups have been examined from the ring inversion barriers and the carbonyl vibrational frequencies with reference to the corresponding data...
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