- Stereoselective synthesis and antiproliferative activity of the isomeric sphinganine analogues
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A flexible synthetic approach to biologically active sphingoid base-like compounds with a 3-amino-1,2-diol framework was achieved through a [3,3]-sigmatropic rearrangement and late stage olefin cross-metathesis as the key transformations. The stereochemistry of the newly created stereogenic centre was assigned via a single crystal X-ray analysis of the (4S,5R)-5-(hydroxymethyl)-4-vinyloxazolidine-2-thione. In order to rationalise the observed stereoselectivity of the aza-Claisen rearrangement, DFT calculations were carried out. The targeted isomeric sphingoid bases were screened in vitro for anticancer activity on a panel of seven human malignant cell lines. Cell viability experiments revealed that C17-homologues are more active than their C12 congeners.
- ?onková, Miroslava,Martinková, Miroslava,Gonda, Jozef,Jacková, Dominika,Pilátová, Martina Bago,Kupka, Daniel,Jáger, Dávid
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- Synthesis of C1–C11 eribulin fragment and its diastereomeric analogues
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A practical stereoselective synthesis of the central C1–C10 fragment of eribulin and its two diastereomeric analogues is developed. Our approach relied on the use of L-ascorbic acid as the starting material which allowed accessing a key intermediate with a syn diol moiety (C9 and C10 of eribulin) and a carboxylic ester group. A functionalized six membered lactone having several required hydroxyl groups was then obtained. In a number of steps, the lactone was converted to an intermediate for our key oxa-Michael reaction. A regio- and stereocontrolled intramolecular oxa-Michael reaction completed the synthesis of the C1–11 fragment having a trans-fused tetrahydropyrans with the exact stereochemistry of various hydroxyl groups, as in eribulin.
- Khatravath, Mahender,Mallurwar, Naveen Kumar,Konda, Saidulu,Gaddam, Jagan,Rao, Pallavi,Iqbal, Javed,Arya, Prabhat
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- Total synthesis of pachastrissamine together with its 4-epi-congener via [3,3]-sigmatropic rearrangements and antiproliferative/cytotoxic evaluation Dedicated to Associated Professor Ladislav Knieo on the occasion of his 70th birthday
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Synthesis of the HCl salts of two anhydrophytosphingosines, jaspine B (1) and its 4-epi-congener 5 from easily available dimethyl l-tartrate and/or l-arabinose, is described. The key transformations are the efficient incorporation of a chiral amino group
- Martinkov, Miroslava,Mezeiov, Eva,Fabikov, Milica,Gonda, Jozef,Piltov, Martina,Moji, Jn
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- Total synthesis of pachastrissamine together with its 4-epi-congener via [3,3]-sigmatropic rearrangements and antiproliferative/cytotoxic evaluation Dedicated to Associated Professor Ladislav Knie?o on the occasion of his 70th birthday
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Synthesis of the HCl salts of two anhydrophytosphingosines, jaspine B (1) and its 4-epi-congener 5 from easily available dimethyl l-tartrate and/or l-arabinose, is described. The key transformations are the efficient incorporation of a chiral amino group
- Martinková, Miroslava,Mezeiová, Eva,Fabi?íková, Milica,Gonda, Jozef,Pilátová, Martina,Moj?i?, Ján
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- Facile synthesis of (2R,3S)-2-benzyloxy-3-hydroxybutyrolactone
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The heterocyclic diols derived from L-dimethyl tartrate are important chiral synthons in organic synthesis. In particular, L-threosolactone and L-threosolactam structures are versatile precursors for the synthesis of biologically active molecules. Structu
- El-Batta, Amer
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p. 2457 - 2463
(2013/07/25)
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- Diastereoselective synthesis of all eight L-hexoses from L-ascorbic acid
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A novel versatile method for the synthesis of all eight diastereomerically pure L-hexoses was developed. L-Ascorbic acid was converted to two diastereomers A. These α-hydroxy esters were transformed into four γ-alkoxy- α,β-unsaturated esters C via the int
- Ermolenko, Ludmila,Sasaki, N. Andre
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p. 693 - 703
(2007/10/03)
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- Synthesis of (1R,2S)- and (1S,2S)-3-azido-1,2-dihydroxypropylphosphonates
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An efficient synthesis of diastereomerically pure dimethyl (1R,2S)- and (1S,2S)-3-azido-1,2-dihydroxypropylphosphonates from L-ascorbic acid, via new chirons: (2S,3S)-4-azido-3-benzyloxy-1,2-O-isopropylidene-1,2-butanediol and (2S)-3-azido-2-benzyloxypropanal was elaborated.
- Wroblewski, Andrzej E.,Glowacka, Iwona E.
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p. 989 - 994
(2007/10/03)
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- The first total synthesis of (+)-rogioloxepane A
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The first total synthesis of (+)-rogioloxepane A is described. The α,ω-trans-disubstituted oxepene skeleton was stereoselectively constructed via cyclization of the hydroxy epoxide promoted by the (Bu3Sn)2O/Zn(OTf)2 system. The proposed configurations of 6R and 13R were confirmed through this synthetic study.
- Matsumura, Ryuji,Suzuki, Toshio,Hagiwara, Hisahiro,Hoshi, Takashi,Ando, Masayoshi
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p. 1543 - 1546
(2007/10/03)
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- Visible Light Initiated Photosensitized Electron Transfer Cyclizations of Aldehydes and Ketones to Tethered αβ-Unsaturated Esters: Stereoselective Synthesis of Optically Pure C-Furanosides
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Photosensitized one-electron reductive activation of aldehydes/ketones tethered with activated olefins leads to efficient cyclization to give diastereoselective cycloalkanols in high yield. The activation is promoted by secondary and dark electron transfer from visible light (405 nm) initiated photosensitized electron transfer generated 9,10-dicyanoanthracene radical anion (DCA.-). The DCA.- is produced by electron transfer using either triphenylphosphine (Ph3P) as sacrificial electron donor (PS-A) or 1,5-dimethoxynaphthalene (DMN) as primary electron donor and ascorbic acid as sacrificial electron donor (PS-B), to light-absorbing DCA. The cyclization is suggested to involve ketyl radical intermediate. High trans diastereoselectivity is observed during the formation of cycloalkanols. This cyclization strategy is further extended for the stereoselective synthesis of optically pure C-furanoside (41), starting from naturally occuring L-tartaric acid. The stereochemistry of 41 is suggested based on the single-crystal X-ray diffraction data.
- Pandey, Ganesh,Hajra, Saumen,Ghorai, Manas K.,Ravi Kumar
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p. 5966 - 5973
(2007/10/03)
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- Total synthesis of an enantiomeric pair of FR980482. 2. Syntheses of the aromatic and the optically active aliphatic segments
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The synthesis of the aromatic segment 4 was achieved starting from commercially available 5-hydroxyisophthalic acid (6) by utilizing Claisen rearrangement of 9, bromolactonization of 12, and modified Curtius rearrangement of 16 as the key steps. Furthermore, the optically active aliphatic segments 5 and ent-5 were synthesized in enantiomerically pure forms starting with natural (2R, 3R)- and unnatural (2S, 3S)-diethyl tartrate (7 and ent-7), respectively: The synthetic scheme features epoxide formation of 26, nucleophilic epoxide opening of 27 with an azide anion, reduction of the azide function in 33 to an amine, and formation of the N-protected 1,3-oxazolidine 35.
- Yoshino, Toshiharu,Nagata, Yuriko,Itoh, Etsuko,Hashimoto, Masaru,Katoh, Tadashi,Terashima, Shiro
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p. 10239 - 10252
(2007/10/03)
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- Stereoselective syntheses and reactions of chiral oxygenated α,β-unsaturated-γ- and δ-lactones
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The syntheses of the chiral α,β-unsaturated lactones (+)-5, (-)-6, (+)-8, (+)-9, and (+)-10 have been efficiently achieved from readily available starting materials. The lactone (+)-5 has been synthesized in 7 steps from (R,R)-dimethyl tartrate (38-43% overall yield). The use of (+)-5 in formal syntheses of natural (+)-asperlin 4 and advanced intermediates for (+)-olguine 2 are also reported. The lactone (-)-6 has been prepared in 5 steps from (R)-malic and (44-50% overall yield). It can be a useful precursor for the syntheses of branched chain and deoxy nucleoside analogues. The preparation of (-)-6 constitutes formal syntheses of natural (+)-eldanolide 53 and the (+)-Geissman-Waiss lactone 54 (an intermediate for the syntheses of a variety of pyrrolizidine alkaloids). The lactones (+)-8, (+)-9 and (+)-10 have been synthesized from 3,4-di-O-acetyl-L-rhamnal 58. The highly diastereoselective transformations of (+)-9 and (+)-10, through sequential conjugate nucleophilic addition and enolate reaction, into densely functionalized chiral γ-lactones 12 are also reported. Copyright (C) Elsevier Science Ltd.
- Sanchez-Sancho, Francisco,Valverde, Serafin,Herradon, Bernardo
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p. 3209 - 3246
(2007/10/03)
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- C-Furanoside Synthesis via Radical Cyclisation of β-Alkoxyacrylates
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Stereoselective synthesis of C-furanosides is accomplished via tributylstannane-mediated radical cyclisation of β-alkoxyacrylates.
- Lee, Eun,Park, Cheol Min
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p. 293 - 294
(2007/10/02)
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- Preferred conformation of C-glycosides. 12. Synthesis and conformational analysis of α,α-, α,β-, and β,β-C-trehaloses
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A single, unified strategy for the stereocontrolled synthesis of α,α-, α,β-, and β,β-C-trehaloses (1-3) was developed. The solution conformations of C-trehaloses 1-3, as well as their permethyl derivatives, were determined on the basis of vicinal coupling constants observed in the 1H NMR spectra. The preferred conformations for α,α- and β,β-C- trehaloses (1 and 3), shown in Figure 1, were predicted and experimentally proven. A diamond-lattice analysis of α,β-C-trehalose (2), shown in Figure 2, revealed the relative stability of the three staggered conformers to be 2A > 2B > 2C, and the experimental data were found to be consistent with this trend. It was demonstrated that the inversion of the C.2 or C.2' hydroxyl group of 2 affected its conformational preference in a predictable manner. The 1H NMR spectra of α,β-C-trehalose 2 provided direct experimental evidence to illustrate that the α-C-glycosidic bond is conformationally more rigid than the β-C-glycosidic bond.
- Wei,Kishi
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- Total synthesis of (+)-colletodiol from (S,S)-tartrate and (R)-3-hydroxybutanoate
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The macrodiolide antibiotic (+)-colletodiol (7, Scheme 1) was synthesised.The configuration was thus proven to be (6R,11R,12R,14R). - Key intermediates (Schemes 9 and 10) are the two hydroxy acids 43 and 64, which were prepared from dimethyl (S,S)-tartrate in 20percent overall yield (12 steps) and from (R)-3-hydroxybutanoate in 57percent overall yield (6 steps), respectively.The two hydroxy acids were cyclised to give, after deprotection, the title compound. - Our investigations led to the production of a large number of chiral building blocks, many of them in different stereoisomeric forms.
- Schnurrenberger, Peter,Hungerbuehler, Ernst,Seebach, Dieter
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p. 733 - 744
(2007/10/02)
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- STEREOSELECTIVE ALLYLATION FOR PREPARATION OF L-HEXOSE DERIVATIVES
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The reaction of allyltrimethylsilane with α,β-dialkoxyaldehydes is catalyzed by magnesium bromide, and provides for a highly stereoselective allylation which is predicted by α-chelation of the Lewis acid.The observed stereocontrol is opposite to that gene
- Williams, D. R.,Klinger, Franz D.
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p. 869 - 872
(2007/10/02)
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- THE USE OF L-TARTARIC ACID IN THE SYNTHESIS OF ENANTIOMERICALLY PURE COMPOUNDS: SYNTHESIS OF 4-O-BENZYL-2,3-DIDEOXI-L-THREO-HEX-2-ENONO-1,5-LACTONE
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The title compound was obtained through a seven steps sequence and using -dimethyl L-tartrate as the starting material (30percent overall yield).The system 2,3-dideoxy-L-threo-hex-2-enono-1,5-lactone is present in several natural compounds.
- Valverde, Serafin,Herradon, Bernardo,Martin-Lomas, M.
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p. 3731 - 3734
(2007/10/02)
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- AN EFFICIENT AND STEREOSELECTIVE SYNTHESIS OF PLATELET-ACTIVATING FACTORS AND THE ENANTIOMERS FROM D- AND L-TARTARIC ACIDS
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Acetyl glyceryl ether phosphorylcholines, platelet-activating factors (1 and 2), were efficiently synthesized in a stereochemically unambiguous manner starting from D- and L- tartaric acids as the chiral synthons.
- Fujita, Kagari,Nakai, Hisao,Kobayashi, Susumu,Inoue, Keizo,Nojima, Shoshichi,Ohno, Masaji
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p. 3507 - 3510
(2007/10/02)
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