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1.
Two steroids, 3-oxo-chol-4-ene-24-oic acid () andi ts unsaturated analog have been isolated from the dorid nudibranch , and the acid has been shown to have antifeedant properties. 相似文献
2.
Charles J. Simmons Franz-Josef Marner John H. Cardellina Richard E. Moore Karl Seff 《Tetrahedron letters》1979,20(22):2003-2006
The crystal structure of pukeleimide C, a novel pyrrolic compound from a shallow-water variety of the marine blue-green alga , is reported. 相似文献
3.
N-Acyl derivatives of ,-acosamine and ,-ristosamine were synthesized with high stereo selectivity utilizing intramolecular Michael addition of γ- and δ-carbomoyloxy-α,β-unsaturated esters. 相似文献
4.
Hideo Kigoshi Yoshikazu Shizuri Haruki Niwa Hiyoyuki Yamada 《Tetrahedron letters》1982,23(14):1475-1476
Isolation and structural elucidation of two new acetylenic polyenes, -laurencenyne and -neolaurencenyne from the marine red alga were carried out, the former compound very recently being proposed to be a biosynthetic precursor of the C15 halogenated cyclic ethers, and . 相似文献
5.
Claudio Fuganti Piero Grasselli Giuseppe Pedrocchi-Fantoni 《Tetrahedron letters》1981,22(40):4017-4020
The synthesis of N-benzoyl--daunosamine (14) from the C4 aldehyde (2b), prepared from -threonine, through the intermediacy of the C7 adduct (7a) is reported 相似文献
6.
A stereOselective conversion of 1,8- and 1,5-diethoxy-9,10-anthraquinone to 1,8- and 1,5-diketo----perhydroanthracenes by successive sodium borohydride, metal-ammonia, and catalytic reductions is described. 相似文献
7.
J Leitich 《Tetrahedron letters》1980,21(32):3025-3028
The relative rates of formation of and [2+2]cycloadducts of benzyne to , - and , -1,5-cyclooctadiene, - and -cyclooctene are discussed and properties of the adducts (e.g., their unusual hydrogenation) are described. 相似文献
8.
Hans Achenbach Andreas Mühlenfeld Benno Weber G.U. Brillinger 《Tetrahedron letters》1982,23(45):4659-4660
The new compounds – and have been isolated from cultures of 相似文献
9.
Ronald J. Quiann Richard P. Gregson Alan F. Cook Robert T. Bartlett 《Tetrahedron letters》1980,21(6):567-568
A new pharmacologically active agent isolated from the marine sponge has been identified as 1-methylisoguanosine () by spectral and degradative chemical methods and synthesis from a β-D-ribofuranosylimidazole (). 相似文献
10.
Toshihiro Hashimoto Motoo Tori Zenei Taira Yoshinori Asakawa 《Tetrahedron letters》1985,26(52):6473-6476
Four novel fusicoccane diterpenoids, fusicoplagins A, B, C, and D, have been isolated from the liverwort subsp. and the structures determined by spectroscopic methods, chemical transformations, and X-ray crystallographic analysis. 相似文献
11.
A new ichthyotoxic toxin was isolated from the unialgal culture of the deleterious Florida red tide organism, Davis (Syn. ), and its structure was elucidated. 相似文献
12.
Sterepolide and dihydrosterepolide, new sesquiterpenes isolated from the fungus , are assigned structures and , respectively. The assignments are based mainly on spectroscopic studies and similarities to isolactarorufin (). A possible mode of biogenesis of these isolactarane type sesquiterpenes is discussed. 相似文献
13.
The 1H and 13C nmr spectra of , -9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d6 or alkaline D2O, clearly show that it exists in a --conformation with carboxyl groups, thus being the first case of - preference of a bicyclo[3.3.1] nonan-9-one due to the presence of ,-2,4- substituents. 相似文献
14.
Giovanni Fronza Claudio Fuganti Piero Grasselli Giulio Marinoni 《Tetrahedron letters》1979,20(40):3883-3886
The enantiomeric alcohols () and (), obtained from (2,3) tartaric acid and, respectively, -threonine, have been used to construct the C6, enantiomeric deoxy amino sugar derivatives () and () 相似文献
15.
The Structure elucidation of the title compounds, two new insecticidal components of the marine red alga Yamada, is described. 相似文献
16.
Treatment of halo--methylphosphonium salts with potassium fluoride and halogen (I2, Br2, ICl, IBr) gives modest yields of halo--methanes. This method of preparation augments the classical Hunsdiecker approach to these materials. 相似文献
17.
The structures and syntheses of prenylhydroquinone (), 6-hydroxy-2,2-dimethylchromeme (), and prenylquinone (), which are natural products isolated from the marine colonial tunicate , are described. Prenylhydroquinone shows activity against P388 lymphocytic leukemia (T/C=138). Both and significantly inhibit the mutagenic effects of benzo(a)pyrene, aflatoxin B1 and ultraviolet light on , and may be cancer protective agents. 相似文献
18.
A new purine derivative with cytokinin activity was isolated from the cuckoo-pint fruits () and identified as 6-(o-hydroxybenzylamino)-2-methylthio-9-β-D-glucofuranosylpurine . 相似文献
19.
Eiichi Kitazawa Akira Ogiso Shuji Takahashi Masaaki Kurabayashi Harumitsu Kuwano Tadashi Hata Chihiro Tamura 《Tetrahedron letters》1979,20(13):1117-1120
Two new diterpenelactones named plaunol A () and B () exhibiting anti-Shay ulcer activity were isolated from Thai medicinal plant, . Structure of was determined by X-ray analysis of its -bromobenzoate and structure of was deduced from the results of chemical correlation and the spectral data. 相似文献
20.
The nitration of -cresol by nitric acid in aqueous sulphuric acid involves ~40% -substitution at CMe. The 4-methyl-4-nitrocyclohexa-2,5-dien-1-one (I) formed undergoes an acid-catalysed rearrangement to 4-methyl-2-nitrophenol. 相似文献