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1.
The novel structures assigned by Yunusov et al to the C19-diterpenoid alkaloids, acomonine (), iliensine (), 14-dehydroiliensine (), and 14-bensoyliliensine () have been found to be in error. We have demonstrated that these alkaloids are identical with the well-known alkaloids, delsoline (), delcosine (), 14-dehydrodeloosine (), and 14-benzoyldelcosine (), respectively. 相似文献
2.
Motomasa Kobayashi Yutaka Kiyota Satomi Orito Yoshimasa Kyogoku Isao Kitagawa 《Tetrahedron letters》1984,25(34):3731-3734
Five new pregnene-type steroidal glycosides, named pregnedioside -a (), 4′-O-acetyl-pregnedioside-a (), 3′-O-acetyl-pregnedioside-a (), pregnedioside-b (), and 4′-O-acetyl-pregnedioside-b (), were isolated from an Okinawan soft coral of Alcyonium sp. and their structures were elucidated. These are rare examples of steroidal gylcosides from soft coral. 相似文献
3.
A new synthesis of the pyranoquinolone alkaloids flindersine (), 8-methoxyflindersine (), N-methylflindersine (), zanthobunglanine () oricine () and veprisine () and the prenylquinolone alkaloids atanine (), preskimmianine () N-methylatanine (), O-methylglycosolone () and N-methylpreskimmianine () is described. 相似文献
4.
Pyrolysis of homoadamant-3-ene (), generated from 1-adamantylcarbene (), leads to the same three olefins (, , and ) that are produced from pyrolysis of 3-homoadamantyl acetate (). 相似文献
5.
Starting from 4, 5, 12, 13-tetrakis(methoxycarbonyl)[2.2]paracyclophane (), the penta-(), hexa-(–), hepta-(), and octamethyl-() derivatives have been prepared by a repetitive formylation-reduction sequence. 相似文献
6.
The structures and syntheses of prenylhydroquinone (), 6-hydroxy-2,2-dimethylchromeme (), and prenylquinone (), which are natural products isolated from the marine colonial tunicate , are described. Prenylhydroquinone shows activity against P388 lymphocytic leukemia (T/C=138). Both and significantly inhibit the mutagenic effects of benzo(a)pyrene, aflatoxin B1 and ultraviolet light on , and may be cancer protective agents. 相似文献
7.
Emir Valencia Inge Weiss Sadiqa Firdous Alan J. Freyer Maurice Shamma Alejandro Urzús Victor Fajardo 《Tetrahedron》1984,40(20):3957-3962
Three Chilean barberries, Mart. ex Schult., . Hook and [ulbar|B. Phil. (Berberidaceae), have yielded several new isoindolobenzazepine and protoberberine alkaloids. Novel isoindolobenzazepines are (±)-13-deoxychilenine (), pictonamine (), chileninone (), (±)-chileniimi () and (±)-palmanine (). Highly oxidized protoberberines of particular interest include (±)-O-methylprechilenine () and (±)-prepseudopalmanine (), together with 13-methoxy-8-oxyberberine (). Isoindolobenzazepine alkaloids arise biogenetically from the rearrangement of highly oxidized protoberberines. 相似文献
8.
Hisashi Ishii Tsutomu Ishikawa Ih-Sheng Chen Sheng-Teh Lu 《Tetrahedron letters》1982,23(42):4345-4348
The structures of three new prenylphenyl propanoids, wutaiensol (), wutaiensal (), and methyl demethoxywutaiensate () were established by correlating with S-rutaretin methyl ether () or S-marmesin () by chemical means. The structure of wutaialdehyde (), a related compound, was also established by total synthesis of the racemate and by correlating with . Preliminary piscicidal test on these compounds disclosed that and are weakly bu distinctly positive. 相似文献
9.
A route towards I-oxygenated eudesmanolides, via a (2+2) photocycloaddition reaction for constructing the decalin framework is described. The following natural substances have been synthesized. (=)-dihydroreynosin (), (±)-1- oxo-dihydronmagnolialide (), (±)-maritimin (), (±)-dihydromagnolialide (), (±)-magnolialide (), (±)-dihydrosantamarine (). Also a synthesis of (±)--santonin () is presented. 相似文献
10.
Reaction of the cyclic 1, 3-dicarboxylic acid derivatives (), () and () with (R)- or (S)-citronellal (/) gives the enantiomeric tricyclic dihydropyrans (), (), () and (), probably via a 100% stereocontrolled intramolecular cycloaddition. 相似文献
11.
Athelstan L.J. Beckwith George Phillipou Algirdas K. Serelis 《Tetrahedron letters》1981,22(29):2811-2814
The rates and stereochemistry of ring closure of the radicals (), (), (), and () have been determined and rationalised. 相似文献
12.
The protection of the 6-oxo group of deoxyguanosine with the 2-trimethylsilylethyl (), phenylthioethyl (), 4-nitrophenylthioethyl (), 4-nintrophenethyl (), and cyanoethyl () groups is described. Each protecting group is introduced in good yield and is cleaved under mild conditions. Compatibility with the various approaches to oligonucleotide synthesis is discussed. 相似文献
13.
The 6-hydroperoxy-1,4-cyclooctadiene (), which is formed in the photosensitized oxygenation of 1,5-cyclooctadiene (), affords on further singlet oxygenation 5,8-dihydroperoxy-1,3-cyclooctadiene (), which via triphenylphosphine reduction leads to -5,8-dihydroxy-1,3-cyclooctadiene () and subsequent pyridinium chlorochromate oxidation to 1,3-cyclooctadien-5,8-dione (). 相似文献
14.
Homolytic addition reaction of N-halosulfoximides, i.e., diphenyl-N-chloro sulfoximide(), diphenyl-bromosulfoximide(), and methylphenyl-N-chloro-sulfoximide(), to such olefins as tert-butylethylene and cyclohexene was found to afford the corresponding N-alkylated sulfoximides, which are presumed to be formed via the initial addition of the sulfoximidoyl radical. 相似文献
15.
Yoshito Tobe Yasuyoshi Ueda Masaharu Matsumoto Yasuo Sakai Yoshinobu Odaira 《Tetrahedron letters》1982,23(5):537-538
Bicyclo[6.2.2]dodecadienes (), (), and () having two bridgehead double bonds were synthesized by the pyrolysis of the acetate (). 相似文献
16.
Antonio G. Gonzalez Dulce M. Estrada Julio D. Martin Victor S. Martin Cirilo Perez Ricardo Perez 《Tetrahedron》1984,40(20):4109-4113
The methanol extract of the sponge Spongia officinalis from Pt. Guimar, Tenerife (Canary Islands) contained new diterpenoids which inhibited the growth of microbes. The structures of the new diterpenes isolated were determined as; 11β-hydroxyspongi-12-en-16-one (), 11β-acetoxyspongi-12-en-16-one (), 7β,11β-dihydroxy8pongi-12-en-16-one (), and 7β,11α-dihydroxy-spongi-12-en-16-one (), by spectral and chemical degradation studies. The previously reported diterpenes isoagatholactone () and aplysillin () were also found in the extract. 相似文献
17.
Waldemar Adam Klaus Zinner Adolf Krebs Hermann Schmalstieg 《Tetrahedron letters》1981,22(46):4567-4570
The rather stable 1,2-dioxetanes () and (), derived from the sterically stabilized cyclobutadiene (), exhibit distinct enhanced chemiluminescence behavior, namely energy transfer chemiluminescence (ETC) for () and electron exchange chemiluminescence (EEC) for (). 相似文献
18.
Herbert L. Holland David B. MacLean Russell G.A. Rodrigo Richard F.H. Manske 《Tetrahedron letters》1975,16(49):4323-4326
The reduction product of dehydrocordrastine, , with di-isobutylaluminum hydride spontaneously rearranged to the spirobenzylisoquinolines and , analogous to the alkaloids sibiricine (), corydaine (), and yenhusomidine (). 相似文献
19.
Several atomic metastable species including N(2D), N(2D), N(2P), O(1D2), Ne(3P2), Ar(3P2), Kr(3P2 and Xe(3P2) have been detected by gas phase electron paramagnetic resonance (EPR) in a discharge-flow system. Spectra and absolute concentration are presented. 相似文献
20.
Tetsuji Kametani Keiichiro Fukumoto Hiroshi Kurobe Hideo Nemoto 《Tetrahedron letters》1981,22(37):3653-3656
The acid catalysed cyclization of β-hydroxy selenide (), which was prepared from nerolidol () the epoxide (), was carried out to give bicyclic ether () directly which was further transformed into caparrapl oxide (). 相似文献