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51.
Roberto Martínez Eduardo Corts R. Alfredo Toscano Irma Linzaga 《Journal of heterocyclic chemistry》1990,27(2):363-366
It has been reported that the reaction of β-naphthylamine, dimedone and the appropriate aromatic aldehyde in ethanol gave 1,2,3,4,5,6-hexahydro-2,2-dimethyl-5-aryl-6-aza-9,10-benzophenanthren-4-ones, III , which upon treatment with chromic anhydride, yielded the corresponding tetrahydro derivatives, IV . However, the attempted preparation of these compounds resulted instead of the formation of isomeric acridin-11-ones, V and VI . Structures were confirmed by ir, 1H nmr, ms and X-ray spectroscopy. 相似文献
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Baldomero Esquivel Jorge Cardenas Alfredo Toscano Manuel Soriano-Garcia Lydia Rodriguez-Hahn 《Tetrahedron》1985,41(16):3213-3217
From the aerial parts of Salvia fulgens Cav. (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This novel compound named salvigenolide, showed a six-seven A/B ring system with a trans fussion. A probable biogenetic route is proposed. Its structure and relative stereochemistry as in , were established by spectroscopic means and X-ray diffraction analysis. 相似文献
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Summary The effects of aggregation on the electromagnetic resonance scattering by small, strongly reflecting spheres are studied.
Two or more spheres are allowed to cluster together to form rather complicated anisotropic scatterers whose extinction cross-section
is calculated as a function of the wave number of the incident field in the neighbourhood of the lowest resonance of the individual
spheres. The macroscopic absorption coefficient of a low-density random dispersion of clusters is also calculated in the same
range of wave number. The results for two-, three- and four-sphere clusters are discussed.
Work supported in part by C.N.R. through the G.N.S.M. and in part by the U.S. Army European Research Office through grant
DAJA45-84-C-0005 and contract DAJA37-81-C-0895. 相似文献
60.
Rubén A. Toscano Rachel Mata José Calderon Rosabel Segura 《Journal of chemical crystallography》1996,26(10):707-711
Chloroform/Methanol extraction of the bark ofCedrela salvadorensis (Meliaceae), followed by chromatography afforded the crystalline C28H34O7 terpene. The structure first proposed by spectroscopy is confirmed by this X-ray analysis as 7-acetyloxy-14,15:21,23-diepoxy-4,4,8-trimethyl-d-homo-24-nor-17-oxachola-1,20,22-triene-3,16,-dione. The title compound crystallized in the orthorhombic space groupP212121 with unit cell parametersa=10.243(2),b=13.356(3) andc=18.058(4) Å. The molecule is comprised of a six-membered tetracyclic skeleton, with a circular arc overall conformation. No intermolecular hydrogen bonding is indicated. 相似文献