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1.
Two steroids, 3-oxo-chol-4-ene-24-oic acid (2) andi ts unsaturated analog 4 have been isolated from the dorid nudibranch Aldisasanguineacooperi, and the acid 2 has been shown to have antifeedant properties.  相似文献   

2.
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   

3.
A stereOselective conversion of 1,8- and 1,5-diethoxy-9,10-anthraquinone to 1,8- and 1,5-diketo-trans-syn-trans-perhydroanthracenes by successive sodium borohydride, metal-ammonia, and catalytic reductions is described.  相似文献   

4.
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   

5.
The 1H and 13C nmr spectra of exo, exo-9-oxobicyclo[3.3.1]nonane-2,4-dicarboxylic acid, 3, in DMSO-d6 or alkaline D2O, clearly show that it exists in a boat-chair-conformation with equatorial carboxyl groups, thus being the first case of boat-chair preference of a bicyclo[3.3.1] nonan-9-one due to the presence of exo,exo-2,4- substituents.  相似文献   

6.
The synthesis of N-benzoyl-L-daunosamine (14) from the C4threo aldehyde (2b), prepared from D-threonine, through the intermediacy of the C7 adduct (7a) is reported  相似文献   

7.
Treatment of halo-F-methylphosphonium salts with potassium fluoride and halogen (I2, Br2, ICl, IBr) gives modest yields of halo-F-methanes. This method of preparation augments the classical Hunsdiecker approach to these materials.  相似文献   

8.
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   

9.
Sterepolide and dihydrosterepolide, new sesquiterpenes isolated from the fungus Stereumpurpureum, are assigned structures 4 and 7, respectively. The assignments are based mainly on spectroscopic studies and similarities to isolactarorufin (5). A possible mode of biogenesis of these isolactarane type sesquiterpenes is discussed.  相似文献   

10.
A new ichthyotoxic toxin was isolated from the unialgal culture of the deleterious Florida red tide organism, Gymnodiniumbreve Davis (Syn. Ptychodiscusbrevis), and its structure was elucidated.  相似文献   

11.
The nitration of p-cresol by nitric acid in aqueous sulphuric acid involves ~40% ipso-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   

12.
The enantiomeric alcohols (2) and (11), obtained from (2R,3R) tartaric acid and, respectively, L-threonine, have been used to construct the C6, enantiomeric deoxy amino sugar derivatives (7) and (12)  相似文献   

13.
The amino acid tyrosine has been shown to be the specific precursor of the isonitrile acid 1 produced by Trichodermahamatum (Bon.) Bain. aggr.  相似文献   

14.
The electronic absorption spectra of the four new 12-s-cis-locked retinals (1a–1d) bearing 7-trans, 11-trans double bond geometries are described and compared with those of analogous 7-trans, 11-cis-geometries (1e–1h) and parent retinals (2a-h).  相似文献   

15.
The structures of alkaloid-A and -B were established via X-ray crystallography of the former as its HI salt, and its chemical conversion to the latter.  相似文献   

16.
Two minor lipid components of the brown seaweed Zonariatournefortii were characterized as (all Z) - 5′,7′-dihydroxy-2′-nonadeca-4,7,10,13,16-pentenyl-chrome chromone (3) and 5′,7′-dihydroxy-2′-pentadecylchrome (4).  相似文献   

17.
A new purine derivative with cytokinin activity was isolated from the cuckoo-pint fruits (Zantedeschiaaethiopica) and identified as 6-(o-hydroxybenzylamino)-2-methylthio-9-β-D-glucofuranosylpurine 1.  相似文献   

18.
The EZ 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   

19.
Deuterium labeled dl-6-protoilludene (7) was synthesized and fed to the illudin-producing fungus Omphalotusolearius (ATCC 11719). The hydrocarbon (7) was incorporated into illudin-M (2) and -S (3).  相似文献   

20.
Alkylation of dibutylstannylene complexes of 3,4,6-tri-O-benzyl-D-mannopyranose, methyl 6-O-trityl-α-D-mannopyranoside and methyl α-D-mannopyranoside gives respectively β-D-mannopyranoside and 3-O-alkyl derivatives with high selectivity.  相似文献   

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