共查询到20条相似文献,搜索用时 919 毫秒
1.
The ∠ equilibrium of the cations of benzo hydroxamic acids, in mineral acid, was studied utilizing 1H NMR spectroscopy, NOEDS and MNDO claculations 相似文献
2.
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
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.
Reaction of -(Gly--Cys-Gly)3 with 1,3,5--bromomethylbenzene yields a thioether of the cyclic nonapeptide in 28% yield. Both 1H and 13C NMR spectra are consistent with a molecule of 3-fold symmetry; the temperature dependences of chemical shifts of the amide hydrogens are consistent with a structure composed of three β-turns. 相似文献
5.
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
6.
Perfluoro--propylbromine(V) tetrafluoride has been prepared by fluorination of perfluoro--propyl bromide at 0°C with elemental fluorine. It has been characterized by 19FNMR, mass spectroscopy and elemental analysis. 相似文献
7.
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
8.
L.J. Goad F.-X. Garneau J.-L. Simard J.W. ApSimon M. Girard 《Tetrahedron letters》1985,26(29):3513-3516
- 14α-Methyl-5α-cholest-9(11)-en-3β-ol () and 4α,14α-dimethyl-5α-cholest-9(11)-en-3β-ol () have been isolated from the sea cucumber and characterised by 1H NMR, 13C NMR and mass spectrometry. Lanost-9(11)-en-3β-ol () has also been tentatively identified. The relevance of this series of Δ9(11)-sterols to holothurin biosynthesis is briefly discussed. 相似文献
9.
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
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.
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
12.
A chloro-substituted derivative was prepared from chlorophyll ′. The derivative was shown to be δ-chloro-methyl pheophorbide by UV/VIS, MS and ′H NMR. 相似文献
13.
A new synthesis of (±), (+)- and (-)-lineatin (3,3,7-trimethyl-2, 9-dioxatricyclo [3.3.1.04,7] nonane, ) was achieved. The stereochemistry of (+)-lineatin was established as 1, 4, 5, 7 by an X-ray crystallographic analysis of an intermediate . 相似文献
14.
13C-NMR spectral data on 6-aminohexyl glycosides of -β--galactopyranosyl-2-acetamido-2-deoxy-β--glucopyranose are pr 相似文献
15.
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
16.
A novel olefin metathesis sequence permits ready access to functionalised , , -tricyclo [6.3.0.02,6] undecane based bis-enones. These bis-enones have been shown to undergo cage cyclisation in sunlight with remarkable ease and efficiency. 相似文献
17.
Superoxo Co(III) complexes derived from Co(Salpr) and [Co(CN)5]3? reacted with 2,6-di--butyl--benzoquinone methides to give 2,6-di--butyl--benzoquinone and 2,6-di--butyl-2,5-cyclohexadienonespirooxiranes as the main products, which are considered to result from nucleophilic attack by the superoxo species on the exo double bond of the quinone methides. 相似文献
18.
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
19.
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
20.
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