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1.
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   

2.
A sample of deoxosarcophine (2) was converted into sarcophine (1) by autoxidation. Two reactions are described that will enable the enantiomers of deoxosarcophine to be interrelated.  相似文献   

3.
The structure and absolute stereochemistry of lemnalol (1), a new ylangene-type sesquiterpenoid isolated from the soft coral Lemnaliatenuis Verseveldt, has been established by spectroscopic, chemical, and x-ray crystallographic analyses.  相似文献   

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Starting from the coupling reaction of alkyl cuprates with 1-alkynyl-2-propenyl acetates, the title compounds were prepared by short convenient syntheses.  相似文献   

6.
The structures 1, 2, and 3 have been proposed for three new diterpenes from Dictyotadichotoma mainly on the basis of spectroscopic evidence.  相似文献   

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Ele ven neo-clerodane diterpenoids were isolated from the aerial parts of Linaria saxatilis. Their structures were determined by spectroscopic and chemical methods including the transformation of one of them into the known solidagolactone.  相似文献   

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Four novel polyoxygenated C28-sterols have been identified from the soft coral L. depressum (the Gulf of Eilat, the Red Sea): the 22,28-lactol of 24-methylcholest-5-en-3β,22(R),25-triol-28-al (1), 24-methylcholest-5-en-3β,22(R),25,28-tetraol(2) and the corresponding 5,6β-epoxides (3 and 4).  相似文献   

12.
Four novel fusicoccane diterpenoids, fusicoplagins A, B, C, and D, have been isolated from the liverwort Plagiochilaacanthophylla subsp. japonica and the structures determined by spectroscopic methods, chemical transformations, and X-ray crystallographic analysis.  相似文献   

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1,3,7,9,11,12,14-Heptazapentacene-2,4,8,10 (14H,3H,9H,12H)-tetraones (mixed flavins) were prepared by the cyclization of 1,5-dihydro-8-[N-alkyl-N-(5-nitrouracil-6-yl)-amino-5-deazaflavins with Vilsmeier reagent. The mixed flavins oxidized alcohol under neutral condition in sunlight and a remarkable autorecycling was observed.  相似文献   

16.
A new tricyclic C12 hydrocarbon, inflatene (1), possessing unexpected ichthyotoxic properties, has been isolated as the major metabolite of the stoloniferan Clavularia inflata var. luzoniana. The structure of inflatene was secured by extensive FT-NMR studies with the natural product and several key derivatives.  相似文献   

17.
N-Acyl derivatives of D,L-acosamine and D,L-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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J Leitich 《Tetrahedron letters》1980,21(32):3025-3028
The relative rates of formation of cis and trans [2+2]cycloadducts of benzyne to cis, trans- and cis, cis-1,5-cyclooctadiene, trans- and cis-cyclooctene are discussed and properties of the adducts (e.g., their unusual hydrogenation) are described.  相似文献   

20.
Three diterpene acids, representing a new class of bicyclic diterpenes, have been isolated from Bertya dimerostigma F. Muell. (Euphorbiaceae). Spectroscopic and X-ray cryatallographic evidence for their structure is presented. A rationale for their origin via modification of the casbane skeleton is given.  相似文献   

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