共查询到20条相似文献,搜索用时 15 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
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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
3.
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
4.
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
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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.
Claudio Fuganti Piero Grasselli Stefano Servi Carlo Zirotti 《Tetrahedron letters》1982,23(41):4269-4272
The C4erythro and threo diols (7) and (8) are converted either into the chiral epoxides (13) and (15) or into the enantiomers (14) and (16); the epoxide (13) is used as chiral synthon for the preparation of (3,4) 4-methyl-3-heptanol (21). 相似文献
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Penelope W. Codding K.Ann Kerr M.H. Benn Alan J. Jones S.William Pelletier Naresh V. Mody 《Tetrahedron letters》1980,21(2):127-128
The structures of alkaloid- and - were established via X-ray crystallography of the former as its HI salt, and its chemical conversion to the latter. 相似文献
11.
Methods are described for the stereospecific conversion of hydrindenone 3 either to the corresponding fused or fused hydrindanone (1 or 2, respectively.) 相似文献
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Palladium catalysed alkoxycarbonylation of heterocyclic halides affords a simple and versatile synthesis of both and heterocyclic esters where a range of catalysts have been studied and a method to employ inexpensive inorganic bases has been found. 相似文献
14.
The photolysis of diazoindene and diazofluorene at 12K in N2 matrices containing O2 has been studied, using i.r. spectroscopy. The carbonyl oxides, indenone -oxide and fluorenone -oxide, were formed by the reaction of O2 with the corresponding carbenes, and under appropriate conditions could be detected as very photolabile species. Photolysis of indenone -oxide gave indenone and isocoumarin; similar photolysis of fluorenone -oxide gave fluorenone and dibenzopyran-6-one. 相似文献
15.
Cycloaddition reactions between vinyl ethers 3 and -quinone methides 2, thermally generated from 2-hydroxybenzyl alcohols 1, have been studied. The structure and conformational preferences of the 4-substituted 2-ethoxy-(2,3)-dihydro-2-benzopyrans 4–9 obtained, which show new interesting features, are discussed together with competitive kinetic data. The cycloaddition process is concerted and involves -quinone methides in the -configuration. The OEt- transition state seems to be preferred with ethyl vinyl ether and -1-propenyl ethyl ether, whereas with -1-propenyl ethyl ether the stereoselectivity of the cycloaddition process depends on substituents on the methylene group of the starting alcohol 1. These results are discussed in terms of and preference of the propenyl ether methyl group. 相似文献
16.
The amino acid tyrosine has been shown to be the specific precursor of the isonitrile acid produced by (Bon.) Bain. aggr. 相似文献
17.
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
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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