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1.
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
2.
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
3.
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
4.
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
5.
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
6.
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
7.
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
8.
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
9.
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
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.
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
12.
Masaru Inage Haruyuki Chaki Shoichi Kusumoto Tetsuo Shiba 《Tetrahedron letters》1981,22(24):2281-2284
1-α-Monophosphate (), 4′-monophosphate (), and 1-α, 4′-diphosphate () of 6-0-(2-deoxy-2-tetradecanoylamino-6-0-tetradecanoyl-β-D-glucopyranosyl) -2-deoxy-2-tetradecanoylamino-3, 4-di -0-tetradecanoyl-D-glucopyranose were prepared in order to elucidate the role of phosphate moieties in endotoxic activity of lipid A. 相似文献
13.
The biomimetic reactions of epoxygermacrene-D () with basic alumina afforded three new interesting compounds (, , and ), two of which ( and ) have the same carbon skeleton as that of periplanone-A (), a sexual stimulant for the American cockroach. The remaining one () is a bicyclo[3.1.0]hexane derivative, from whch an axisonitrile-3 type compound () has been produced. Finally, preisocalamendiol () was also converted into . 相似文献
14.
Three new electron donors, acenaphtho[5,6-]-1,2-dithiole (), acenaphtho[5,6-]-1,2-diselenole (), and acenaphtho[5,6-]-1,2-ditellurole (), can be prepared in 28%, 22%, and 14% yields respectively by reaction of the elemental chalcogens (S, Se, Te) with 5,6-dilithioacenaphthylene (). Compound is generated by treatment of 5,6-dibromoacenaphthylen (), for which a convenient preparation is described, with -butyllithium (2 equiv.) in THF at ?78°C. 相似文献
15.
Yasuji Yamada Shintaro Nakamura Kazuo Iguchi Kunio Hosaka 《Tetrahedron letters》1981,22(14):1355-1356
Olefinic cyclization of -prenylphenols (), () and () induced by thallium(III) trifluoroacetate was performed. 相似文献
16.
The preparation and use of the suitably substituted tetrahydrohomophthalic anhydride () as a common intermediate for a short regiospecific synthesis of 11-deoxyanthracyclinones, 11-deoxydaunomycinone (), 11-deoxy-carminomycinone (), and 4-demethoxy-11-deoxydaunomycinone () is described. 相似文献
17.
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
18.
-() and -1,3-Butadienylcyclobutane (), all--1-(1 ,3-butadieny1 )-2- vinylcyclobutane (), and all--1,2-bis(1,3-butadienyl)cyclobutane () have been prepared from readily available starting materials, and pyrolyzed to various cyclohexenes. 相似文献
19.
Two new sterols, 26-methylstrongylosterol () and 28-methylxestosterol (), arising from a hitherto unknown quadruple biomethylation sequence, together with the biogenetically important “missing link”, durissimasterol (), were isolated from the Indo-Pacific sponge . 相似文献
20.
cis-1,2-Dibromomagnesiocyclopropane (cis-) was isolated from the reaction of both trans- and cis-1,2-dibromocyclopropane () with magnesium. The corresponding dialkylmagnesium species (), an oligomer of 2-magnesabicyclobutane, was obtained from cis- by precipitation in THF; it forms a soluble complex 8 with HgBr2. 相似文献