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1.
M. Tinggaard P. Hansen P. K. Mogensen O. Simonsen J. Becher 《Journal of heterocyclic chemistry》1989,26(2):439-444
2-Acyl-3-methylthiofurans 3 are obtained in fair yields from 3-methylthio-2-pentene-1,5-dione enolates 1 by reaction with iodine. In a similar reaction 1-phenyl-3-methylthio-4-nitro-2-buten-1-one gave 3-methylthio-2-nitro-5-phenylfuran 11. In the crystalline state the 2-benzoyl-3-methylthio-5-phenylfuran 3b showed a non-bonded sulfur-oxygen interaction as inferred from an X-ray diffraction determination, with a S····O distance of 2.871(5)Å. 相似文献
2.
R. A. Loghry S. Kasina S. H. Simonsen Jay Nematollahi 《Journal of heterocyclic chemistry》1976,13(4):931-932
The structures of two of the three isomeric products of the reactions between cis- and trans-cyclohexanedicarboxylic anhydrides and methylhydrazine were determined by single-crystal X-ray methods to ascertain their tautomeric forms and stereochemistries. One product was found to be cis-N-methylamino-1,2-cyclohexanedicarboximide and the other trans-hexahydro-2-methylcyclohexa[d]pyridazine-1,2-dione. 相似文献
3.
Ronald G. Sutherland Adam Pirko Choi Chuck Lee Stanley H. Simonsen Vincent M. Lynch 《Journal of heterocyclic chemistry》1988,25(6):1911-1916
Synthesis of the heterocyclic skeletons of some biologically active compounds from (η6-o-dichlorobenzene)(η5-cyclopentadienyrl)iron hexafluorophosphate in a two step procedure is described. Cyclopentadienyliron hexafluorophosphate complexes of 1,4-benzodioxino[2,3-b]pyridine, 1,4-benzoxathiino[3,2-b]pyridine, 10H-pyrido[3,2-b]benzoxazine, benzo[b]naphtho[2,3-e][1,4]dioxin, 4-methylbenzo[b]benzopyran-2-one[7,6-e][1,4]dioxin and benzo[b]anthracen-9,10-diono[1,2-e][1,4]dioxin were isolated and characterized. Upon pyrolytic sublimation of these complexes the free heterocycles were obtained and characterized. (η6-1,4-Benzoxathiino[3,2-b]pyridine)(η5-cyclopentadienyl)iron hexafluorophosphate crystalizes in the orthothombic system, space group Pbca; the dihedral angle between the planes of outer rings was found to be 176.8 (1). 相似文献
4.
The structure of 5-hydroxy-trans-2, trans-4-pentadienal acetate has been determined, using three-dimensional diffractometercollected X-ray data. The compound has the all-trans configuration with the atoms C-1 to C-5 in a plane. The charge distribution in the acetate and in the glutacondialdehyde anion have been calculated using the CNDO/2 approximation. In both compounds higher negative charges were found on carbon atoms C-2 and C-4 than on C-1, C-3 and C-5. 相似文献
5.
Nicolaou KC Simonsen KB Vassilikogiannakis G Baran PS Vidali VP Pitsinos EN Couladouros EA 《Angewandte Chemie (International ed. in English)》1999,38(23):3555-3559
Strikingly simple cascade dimerization sequences can be used to assemble the complex frameworks of bisorbicillinoids such as bisorbicillinol (1), bisorbibutenolide (2), and trichodimerol (3). The mechanistic facets of the biomimetic total syntheses of these bioactive natural products were also explored. Inspection of the unique molecular architecture of these compounds reveals that they are likely to be assembled in nature by a dimerization of two oxidized forms of sorbicillin. 相似文献
6.
We present a method for numerically generating a one-dimensional random surface, defined by the equation x(3)=zeta(x(1)), that suppresses single-scattering processes in the scattering of light from the surface within a specified range of scattering angles. Rigorous numerical calculations of the scattering of light from surfaces generated by this approach show that the single-scattering contribution to the mean scattered intensity is indeed suppressed within that range of angles. 相似文献
7.
8.
Michio Kimura Stanley H. Simonsen Steven R. Caldwell Gary E. Martin 《Journal of heterocyclic chemistry》1981,18(3):469-473
The single crystal X-ray diffraction structure of 2-(2′-pyridylthio)-3-nitropyridine is reported. A non-bonded interaction was observed between the sulfur atom and one of the oxygen atoms of the nitro group with an interatomic distance of 2.678 A. Examination of the molecule's behavior in solution by 13C-nmr spin-lattice (T1) relaxation measurements showed the non-nitro bearing pyridyl ring to reorient anisotropically about the C2′-C5′ bond axis. In contrast, the nitro substituted pyridine ring did not appear to exhibit anisotropic reorientation about the corresponding C2-C5 bond axis. Rather, approximately equivalent relaxation times were noted for all protonated ring carbons, indicating that the relaxations of this portion of the molecule were governed by the overall isotropic reorientation of the system. Based on these observations, it was concluded that the intramolecular sulfur-nitro interaction also operates in the solution state and is sufficiently strong to prevent free rotation of the substituted portion of the molecule about the C2-S bond axis. 相似文献
9.
10.
Phase locking and supermode selection in multicore photonic crystal fiber lasers with a large doped area 总被引:6,自引:0,他引:6
Michaille L Bennett CR Taylor DM Shepherd TJ Broeng J Simonsen HR Petersson A 《Optics letters》2005,30(13):1668-1670
We report on the laser properties of multicore photonic crystal fiber lasers. A stable phase locking of six- and seven-core structures through evanescent coupling is observed. Effective supermode selection is obtained by using both diffraction losses and the Talbot effect. A pure in-phase supermode is obtained (1.1 times diffraction limited). The laser operating in this mode has a slope efficiency of 70% with up to 44 W of output power. The modal area of the in-phase supermode multicore fiber is 1150 microm2, which makes it, to our knowledge, the single-mode fiber laser with the largest mode field area. In-phase laser action is stable when the fiber is bent. 相似文献