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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.
Nmr and UV studies show that -dimethylamino--bromostyrene, I, undergoes SNl reaction in H2O and HClO4 (kSNl = 6 × 10?1sec.?1 at 25°). The vinyl cation has an extraordinary selectivity for capture by aromatic amines relative to H2O, including I itself to give the dimer II. 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.
Joseph Hakl 《Thermochimica Acta》1984,80(2):209-219
The instrument described is suitable for the investigation of the thermal behaviour of substances and reaction mixtures under production conformable conditions; this is made possible by the sophisticated design of the sample chamber: easy stirring of the samples, measuring under any gas atmosphere and while bubbling gas through the sample, choice of the sample container and visual observation during the measurement. The control device allows the choice of one of three operational modes: constant temperature, linear increase in temperature, and adiabatic control; this permits the application of the SEDEX apparatus for a variety of methods including dynamic scanning, isoperibolic measurements, and (quasi) adiabatic studies. 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.
Two steroidal compounds BR-1 (I) and ?2 (II) which had been obtained from the rhizomes of Baker, were isolated also from those of Roth. They were identified, respectively, by X-ray analysis and chemical correlation as 1β,2β,3β,4β,5β,7α-hydroxy-spirost-25(27)-en-6-one and its corresponding 6β-hydroxy compound. 相似文献
7.
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
8.
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
9.
Monomeric -dimethylamino--bromostyrene undergoes SNl increasingly slowly in 60 to 91% dioxane. Reaction is catalyzed by HClO4, NaOH and NaClO4. Dimer 11 reverts to monomer I in 91% dioxane. There is only a small solvent effect on the solvolysis rate of II. 相似文献
10.
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
11.
All four isomers of substituted 3-alkylthio-4-hydroxybutenes have been synthesised: both the geometry of the double bond and the relative stereochemistry of the two chiral centres are controlled. 相似文献
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Michael J. Cook Michael H. Abraham Luigi E. Xodo Raymond Cruz 《Tetrahedron letters》1981,22(31):2991-2994
Head space analysis, GLC retention time data, and solution calorimetry are used to determine the effect of medium on the thermodynamic parameters for the equilibrium (1) ? (2). It is shown that changes in ΔG° and ΔH° can be evaluated for the transfer of the equilibrium from a series of solvents to the gaseous phase which is used as the reference medium. 相似文献
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Andrew Pelter James A. Ballantine Peter Murray-Rust Victor Ferrito Alexander F. Psaila 《Tetrahedron letters》1978,19(21):1881-1884
The structure of anhydrobonellin (II) has been proposed by spectroscopic techniques and confirmed by single crystal X-ray diffraction. The relationship of (II) to bonellin is clear and thus the structure of bonellin is certain. 相似文献