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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   

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Isolation and structural elucidation of two new acetylenic polyenes, trans-laurencenyne 1 and trans-neolaurencenyne 2 from the marine red alga Laurencia okamurai were carried out, the former compound 1 very recently being proposed to be a biosynthetic precursor of the C15 halogenated cyclic ethers, 7 and 8.  相似文献   

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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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The structures of two unique sesterpenes, toxislylide A and B, have been deduced by chemical, spectral, and x-ray crystallographic studies. They are components of the sponge Microcionatoxistyla.  相似文献   

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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   

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Methods are described for the stereospecific conversion of hydrindenone 3 either to the corresponding trans fused or cis fused hydrindanone (1 or 2, respectively.)  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   

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