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1.
Shuji Yamashita 《Tetrahedron》2011,67(35):6616-6626
Ciguatoxins, the principal causative toxins of ciguatera seafood poisoning, are potent toxic polycyclic ethers. In this paper, we report a stereoselective and secure route to the left wing of Caribbean ciguatoxin on the basis of a 6-exo radical cyclization strategy. 相似文献
2.
Ciguatoxin C-CTX-1 was isolated as a principal causative toxin of ciguatera seafood poisoning in the Caribbean Sea, and is structurally classified as a ladder-shaped polycyclic ether. In this Letter, we report the synthesis of the tricyclic LMN-ring system of C-CTX-1. SmI2-mediated reductive cyclization efficiently constructed the seven-membered M-ring with the axially oriented 1,3-dimethyl structure. 相似文献
3.
Atsushi TatamiMasayuki Inoue Hisatoshi UeharaMasahiro Hirama 《Tetrahedron letters》2003,44(28):5229-5233
A concise route to the HIJKLM-ring fragment 10 of ciguatoxin (CTX) and 51-hydroxyCTX3C was developed in which oxiranyl anion addition and intramolecular carbonyl olefination were utilized as key transformations. The present procedure requires only 23 steps from the I-ring 5, while 35 steps were employed in a previous synthesis of the corresponding right wing 11 of CTX3C. The high efficiency of the present synthesis ensures a supply of 10 for total synthesis and biomedical applications. 相似文献
4.
The A-E fragment of the marine natural product CTX3C has been prepared in an efficient manner by using a strategy in which two-directional and iterative ring-closing metathesis (RCM) reactions were employed for ring construction. 相似文献
5.
Ciguatoxin C-CTX-1 was isolated as a principal causative toxin of ciguatera seafood poisoning in the Caribbean Sea, and is structurally classified as a ladder-shaped polycyclic ether. In this Letter, we report the convergent synthesis of the pentacyclic left half of C-CTX-1, based on a newly developed acyl radical strategy. 相似文献
6.
Hiroyoshi Takamura Takashi Abe Naoki Nishiuma Rie Fujiwara Takahiko Tsukeshiba Isao Kadota 《Tetrahedron》2012,68(10):2245-2260
A convergent synthesis of the right-hand fragment of ciguatoxin CTX3C was investigated. The first and second generation stereocontrolled syntheses of the LM ring fragment were achieved via spiroacetalization as a key step, respectively. The polyether framework of the HIJKLM ring fragment was constructed in a convergent manner by using intramolecular allylation, ring-closing metathesis, and stereoselective hydrogenation to form the 36-methyl substituent as the key transformations. 相似文献
7.
A tricyclic model ether compound comprising 6/8/6 ether rings was synthesized via a new route including conjugate addition to form a symmetric eight-membered ether-ketone with syn/trans stereochemistry in selective manner. The corresponding vinyl triflate of this ketone was allowed to convert to the vinyl methyl derivative via cross-coupling reaction. This endo-olefinic tetrahydro-2H-oxocin was selectively reduced to afford α-methyl product. The corresponding exo-olefinic oxocane derivative, on the other hand, provided the β-methyl isomer as the major diastereoisomer (2/1). Our previous report on the synthesis of this final product was revised due to some rearrangement and the mechanisms are discussed. 相似文献
8.
Hirama M 《Chemical record (New York, N.Y.)》2005,5(4):240-250
After a twelve-year struggle, the total synthesis of ciguatoxin CTX3C has been achieved. Annually, more than 20,000 people worldwide suffer from ciguatera seafood poisoning. The extremely small amounts of the causative neurotoxin, ciguatoxin, in fish hampered the isolation, structural elucidation, detailed biological study, and preparation of anti-ciguatoxin antibodies for detecting these toxins. The large (3 nanometers long) and complicated molecular structure of ciguatoxins hindered chemists from completing a total synthesis. The chemical synthesis of CTX3C, determination of the absolute configuration, and synthesis-based preparation of the monoclonal antibodies as well as the effect of synthetic CTX3C on voltage-sensitive sodium channels are outlined. 相似文献
9.
A fully functionalized ABCDE ring moiety of ciguatoxin (CTX), the major causative agent of ciguatera poisoning, was synthesized for the first time. The present strategy involves the efficient installation of the C5-dihydroxybutenyl substituent and construction of the tetrahydrooxepin E ring using a novel alpha-chlorosulfide synthon. [structure: see text] 相似文献
10.
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12.
Synthesis of a tricyclic ring system corresponding to H–I–J rings of ciguatoxin was stereoselectively achieved in 13 steps from a sugar derivative as a model study directed toward the total synthesis of ciguatoxin. 相似文献
13.
A convergent synthesis of the E'FGH ring fragment 28 of ciguatoxin 1B, a principal toxin causing widespread seafood poisonings "ciguatera", has been accomplished through (i) coupling between the E' ring-acetylide 9 and the H ring-aldehyde 20, (ii) stereoselective F ring cyclization via an acetylene cobalt complex, (iii) conversion to a carbonyl function under high-pressure hydrogenation, and (iv) reductive hydroxyketone cyclization to construct the G ring. In the (1)H NMR analysis of 28 at room temperature, a considerable broadening phenomenon was observed due to the slow conformational changes of the FG ring, as reported for natural ciguatoxin 1B. When measured in pyridine at -20 degrees C, the spectra of 28 exhibited a 3.5:1 mixture of two conformational isomers (UP and DOWN conformers). 相似文献
14.
PseudolaricacidAwasisolatedfromPseudolariXkaempferiGord,aChinesemedicinalherbwhichexhibitsantifungalandantifertilityactivities'.Itisaditerpenicacidwithatransfusedhydroazuleneskeletoncontainingfourchiralcenters'.Accordingtotheretrosyntheticanalysis,thetricyclisskeletonofIcouldbeconstructedbyastereoselectiveintramolecular[4 3]cycloadditionfromaseven-memberedlactone4(Schemel).Inthiscommunication,wewouldliketoreportanefficient,stereo-andregio-selective,synthesisoflactone4.Thesynthesisbeganwitht… 相似文献
15.
[reaction: see text] A convergent synthesis of the E'FGH' ring fragment of ciguatoxin has been accomplished through (i) coupling between the E' ring-acetylide and the H' ring-aldehyde, (ii) stereoselective F ring cyclization via an acetylene cobalt complex, (iii) conversion to a carbonyl function, and (iv) reductive hydroxy-ketone cyclization to construct the G ring. 相似文献
16.
A novel compound of butyl crystal violet lactone (BCVL) has been prepared by oxidizing leuco butyl crystal violet lactone
(LBCVL), which was obtained by the mixture of N,N-dibutylaniline, p-(dibutylamino) benzaldehyde and methyl-m-(dibutylamino) benzoate. The structure of BCVL was characterized by 1H-nuclear magnetic resonance (NMR), infrared (IR), and mass spectrometry (MS). The color of BCVL can change reversibly in
some acid or alkali solvents. The result of the dissolution experiment showed that solubility of BCVL in organic solvent was
improved compared with crystal violet lactone (CVL).
Translated from Journal of Fudan University (Natural Science), 2006, 45(3): 375–379 [译自: 复旦学报(自然科学版)] 相似文献
17.
Daisuke Domon Yuko Ohtaniuchi Akihiro Takezawa Sayaka Takeda Hidekazu Kawasaki Akio Murai Hidethoshi Kawai Takanori Suzuki 《Tetrahedron letters》2005,46(48):8279-8283
The C42-C52 part of ciguatoxin CTX3C (1) was synthesized from tri-O-acetyl d-glucal. The synthetic segment had a tetrahydropyran ring corresponding to the ‘C49-reduced’ L-ring of 1, designed to avoid side reactions due to acid-labile C49 acetal carbon during acidic reductive conditions planned in further synthesis toward 1. The vicinal dimethyl part at C47-C48 was constructed by a stepwise conjugate addition/methylation procedure. The C50-C52 unit was installed by Grignard addition of the C3 unit followed by spirocyclization and reductive cleavage of the spirocyclic acetal. Stereoselective assembly of the C42-C44 part was achieved by Brown’s asymmetric crotylboration. 相似文献
18.
Hemigossypol (3), a sesquiterpene natural product, was previously isolated from Gossypium barbadense and was shown to display improved anti-fungal activity compared to gossypol (1), the disesquiterpene dimer of hemigossypol (3). Gossypol exhibits multiple biological activities. In order to study whether hemigossypol and its derivatives retain the various bioactivities of gossypol, we developed a short and convenient synthetic scheme to synthesize hemigossypol. This is the first de novo synthesis of this natural product. In addition derivatives of hemigossypol with various 2,5-alkyl substituents were synthesized. Modification of the synthetic scheme also afforded the natural product hemigossylic lactone (4) and its 2,5-substituted derivatives. 相似文献
19.
一种结构新颖的螺锗化合物的合成 总被引:1,自引:0,他引:1
在吡啶存在下,本文利用手性配体试剂L-N,N-双(2-羟乙基)苏氨酸(1)与β-羧基乙基锗倍半氧化物(2)反应,首次得到一种具有旋光性、含δ-内酯环新颖结构的螺锗化合物(3)。^1H NMR ,IR和MS的测定数据均表明NGe配键是存在的。 相似文献