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1.
An interesting bromine containing compound, laureepoxide (), has been isolated from . Yamada (Rhodomelaceae, Rhodophyta) and its structure has been determined by the chemical degradations and spectral properties. 相似文献
2.
Four novel polyoxygenated C28-sterols have been identified from the soft coral (the Gulf of Eilat, the Red Sea): the 22,28-lactol of 24-methylcholest-5-en-3β,22(R),25-triol-28-al (), 24-methylcholest-5-en-3β,22(R),25,28-tetraol() and the corresponding 5,6β-epoxides ( and ). 相似文献
3.
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
4.
Laurallene (), a new brominated cyclic ether having a terminal allene moiety, has been isolated as a main constituent from the marine red alga Yamada (Rhodomelaceae, Rhodophyta) and its structure was determined by its physical and chemical properties. 相似文献
5.
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
6.
Nancy W. Withers W.C.M.C. Kokke Michel Rohmer W.H. Fenical Carl Djerassi 《Tetrahedron letters》1979,20(38):3605-3608
The sterol fraction of the cultured dinoflagellate contains in addition to cholesterol, 24-methylcholesterol, 4,24-dimethylcholesterol and dinosterol () small amounts of the cyclopropyl-containing sterols gorgosterol () and 5α-gorgostanol () as well as 4α-methylgorgostanol () and E-4α,22ξ,23ξ (or 24ξ)-trimethylcholest-17(20)-en-3β-ol ( or ). The biosynthetic implications of the first isolation of such sterols from a free-living alga are emphasized. 相似文献
7.
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
8.
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
9.
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
10.
Two new tetrahydropyrans have been isolated from the sponge Haliclona sp. From chemical and spectroscopic evidence they are shown to be (1′, 2, 2″, 5, 6)-2-(1′-bromethyl)-2,5-dimethyl-6-(penta-2″,4″-dienyl)-tetrahydropyran and (1′, 2, 5, 6)-2-(1′-bromoethyl)-2,5-dimethyl-6-(pent-4″-enyl)-tetrahydropyran. 相似文献
11.
Bruce M. Howard William Fenical Edward V. Arnold Jon Clardy 《Tetrahedron letters》1979,20(31):2841-2844
The structure of a unique bromine-containing ketal, obtusin (), has been determined by spectral and X-ray crystallographic techniques. Obtusin is a natural component of the Mediteranean red alga . 相似文献
12.
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
13.
The structures of the -illudalane sesquiterpenoids cybrodol ), isocybrodol (), cybrodic acid (), cybrodal (), and trisnorcybrodolide (), are presented. These are the first -illudalanes to be reported. 相似文献
14.
The novel cyclopentenoid monoterpene, gastrolactone (), was synthesized from carvenolide (), and the synthetic material was found to be identical to the natural product by direct comparison. This synthesis confirmed structure which had been suggested earlier on the basis of spectral data. 相似文献
15.
Hiroyuki Kikuchi Yasumasa Tsukitani Kazuo Iguchi Yasuji Yamada 《Tetrahedron letters》1982,23(49):5171-5174
Three new prostanoids, clavulone I(), II() and III(), were isolated from the Japanese Stolonifer Quoy and Gaimard. The structures of these prostanoids were determined on the basis of spectral data and chemical reactions. 相似文献
16.
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
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.
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
19.
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
20.
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