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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.
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
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.
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
5.
Richard E. Moore Walter P. Niemczura Oliver C.H. Kwok Suresh S. Patil 《Tetrahedron letters》1984,25(36):3931-3934
The structure of phaseolotoxin, a toxin produced by cultured pv. , the causal agent of halo blight disease in bean plants is revised to 3. The structure of octicidin, isolated from leaves of bean plants infected with pv. . has been determined to be 4, a protease degradation product of 3 which is formed in the plant. 相似文献
6.
3-Indazol-3-one has been generated by thermolysis of (-azidobenzoyl)iminopyridinium ylide and trapped as its Diels-Alder cycloadducts with several dienes. 相似文献
7.
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
8.
In contrast with the reaction of α-aminonitriles a, the corresponding -acylated α-aminonitriles b-f and oxalyl chloride do not yield pyrazinone derivatives, but 5-aminooxazoles - or 4(5)-imidazolones , the latter being converted in some cases into imidazo [2,1-]isoquinoline-2,5,6(3)-triones. Reactions of compounds b-f and ethyl chlorooxoacetate provide evidence for a 5(4)-iminooxazole intermediate , which aromatizes to yield 5-aminooxazoles -; however, unaromatizable īntermediates of type - isolable as 5(4)y-oxazolones after hydrolysis - undergo a catalyzed Dimroth-type rearrangement to give imidazolone derivatives . 相似文献
9.
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
10.
A range of conjugated ,-dienes have been prepared in a stereo-specific manner acetylene carbocupration: the value of this procedure has been illustrated by an extremely short synthesis of hexadeca-11, 13-dienal a principle component of Navel Orangeworm Pheromone. 相似文献
11.
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
12.
Tadashi Nakata Shigeto Nagao Sachiko Takao Tadasu Tanaka Takeshi Oishi 《Tetrahedron letters》1985,26(1):73-74
(1,3,5)-1,3-Dimethyl]-2,9-dioxabicyclo[3.3.1]nonane has been stereoselectively synthesized based on a highly stereoselective method for the synthesis of 1,3--polyol. 相似文献
13.
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
14.
In strong base, e.g., sodium hydride in dimethylformamide, -(-azidobenzoyl)arylamines cyclise in high yield to 2-aryl-1,2-dihydro-3-indazolin-3-ones. 相似文献
15.
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
16.
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
17.
The structure of engleromycin isolated from Hennings has been established as by spectral techniques. 相似文献
18.
Variously substituted arylazides, as well as -tosylazide, when allowed to react at room temperature with THF previously treated with -butyllithium, undergo a rapid decomposition affording the corresponding amines and fomamides, together with diazomethane. This diazo transfer (with deformylation) reaction is thought to involve the enolate of the acetaldehyde generated by the known cycloreversion of THF in the presence on 相似文献
19.
-Azidophenyl -alkyl ketones in ethanolic potassium hydroxide at room temperature cyclise in high yield to 2,2-dialkylindoxyls. 相似文献
20.
Richard R. Izac Steven E. Poet William Fenical Donna Van Engen Jon Clardy 《Tetrahedron letters》1982,23(37):3743-3746
An ichthyotoxic sesquiterpenoid of unusual structure, pacifigorgiol, has been isolated from the Pacific gorgonian caora . The structure of pacifigorgiol, with relative stereochemistry only, has been defined by a combination of spectral and x-ray crystallographic techniques. 相似文献