- Alkaloids from Alangium javanicum and Alangium grisolleoides that mediate Cu2+-dependent DNA strand scission
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Crude CH2Cl2-MeOH extracts prepared from Alangium javanicum and A. grisolleoides were found to induce DNA strand breakage in the presence of Cu2+ and were subjected to bioassay-guided fractionation to permit identification of the active principle(s). Javaniside (1), a novel alkaloid possessing an unusual monoterpenoid oxindole skeleton, was identified as an active principle contributing to the DNA cleavage activity observed for the crude extract of A. javanicum. Alangiside (2), a tetrahydroisoquinoline monoterpene glucoside widely distributed in the genus Alangium, was also isolated from A. grisolleoides as a new type of Cu2+-dependent DNA cleavage agent. The relative configuration of the asymmetric centers in javaniside was established by analysis of 1H-1H coupling constants and NOESY correlations. Semisynthesis of javaniside from secologanin (3) established the absolute stereochemistry of javaniside.
- Pham, Van Cuong,Ma, Ji,Thomas, Shannon J.,Xu, Zhidong,Hecht, Sidney M.
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- Enantiospecific, diastereoselective synthesis of Aspidosperma alkaloid analogues from secologanin
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Pure enantiomers of two diastereomeric Aspidosperma alkaloid analogues antipodal at the spiro and adjacent centres have been prepared, as kinetic and thermodynamic products, respectively, in a biomimetic sequence via a secodine-like intermediate from a secologanin derivative and Kuehne's indolo- azepine. (C) 2000 Elsevier Science Ltd.
- Brown, Richard T.,Kandasamy, Mythily
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- Bioinspired Divergent Oxidative Cyclization from Strictosidine and Vincoside Derivatives: Second-Generation Total Synthesis of (?)-Cymoside and Access to an Original Hexacyclic-Fused Furo[3,2-b]indoline
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The second-generation synthesis of (?)-cymoside as well as the formation of a new hexacyclic-fused furo[3,2-b]indoline framework is reported. After a Pictet–Spengler condensation between secologanin tetraacetate and tryptamine, the course of the cyclization of the 7-hydroxyindolenine intermediate, generated by oxidation with an oxaziridine, depended on the stereochemistry of the 3-position. The 3-(S)-strictosidine stereochemistry delivered efficiently the scaffold of cymoside via intramolecular coupling with the C16–C17 enol ether, while the 3-(R)-vincoside stereochemistry directed towards the reaction with the C18–C19 terminal alkene and the formation of the unexpected caged compound.
- Dou, Yingchao,Kouklovsky, Cyrille,Vincent, Guillaume
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- Total Synthesis of (-)-Strictosidine and Interception of Aryne Natural Product Derivatives "strictosidyne" and "strictosamidyne"
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Monoterpene indole alkaloids are a large class of natural products derived from a single biosynthetic precursor, strictosidine. We describe a synthetic approach to strictosidine that relies on a key facially selective Diels-Alder reaction between a glucosyl-modified alkene and an enal to set the C15-C20-C21 stereotriad. DFT calculations were used to examine the origin of stereoselectivity in this key step, wherein two of 16 possible isomers are predominantly formed. These calculations suggest the presence of a glucosyl unit, also inherent in the strictosidine structure, guides diastereoselectivity, with the reactive conformation of the vinyl glycoside dienophile being controlled by an exo-anomeric effect. (-)-Strictosidine was subsequently accessed using late-stage synthetic manipulations and an enzymatic Pictet-Spengler reaction. Several new natural product analogs were also accessed, including precursors to two unusual aryne natural product derivatives termed "strictosidyne"and "strictosamidyne". These studies provide a strategy for accessing glycosylic natural products and a new platform to access monoterpene indole alkaloids and their derivatives.
- Anthony, Sarah M.,Tona, Veronica,Zou, Yike,Morrill, Lucas A.,Billingsley, John M.,Lim, Megan,Tang, Yi,Houk,Garg, Neil K.
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p. 7471 - 7479
(2021/05/26)
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- Total Syntheses of (?)-Secologanin, (?)-5-Carboxystrictosidine, and (?)-Rubenine
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The first enantioselective total syntheses of (?)-secologanin (1), (?)-5-carboxystrictosidine (2), and (?)-rubenine (3) were accomplished in 10, 9, and 14 steps, respectively. The key transformation in the synthesis of 1 was a sequential anti-selective or
- Rakumitsu, Kenta,Sakamoto, Jukiya,Ishikawa, Hayato
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supporting information
p. 8996 - 9000
(2019/06/25)
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- Biomimetic synthesis of monoterpenoid indole alkaloids from aglucones of secologanin derivatives: pH controlled product selectivity
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Variation of the pH for hydrolysis of secologanin derivatives with β-glucosidase controls rearrangement of the aglucone to afford different products, and hence stercoselective syntheses of heteroyohimbine, yohimbine and Aspidosperma-type alkaloids; with baker's yeast chemoselective reduction can also be achieved to give a precursor for antirhine and related alkaloids.
- Brown
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p. 609 - 616
(2007/10/03)
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- Enantiospecific synthesis of (-)-3-iso-19,20-dehydro-β-yohimbine from secologanin: A route to normal and pseudo stereoisomers of yohimbine
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Hydrolysis of secologanin ethylene acetal at pH 7 resulted in stereoselective aldol cyclisation to a cyclohexene aldehyde, which, on reductive amination and cyclisation with tryptamine afforded (-)-3-iso-19,20- dehydro-β-yohimbine, converted into various normal and pseudo isomers of yohimbine. (C) 2000 Elsevier Science Ltd.
- Brown, Richard T.,Pratt, Simon B.,Richards, Paul
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p. 5627 - 5630
(2007/10/03)
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- Con figurative correlation and conformational analysis of strictosidine and vincoside derivatives
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On the basis of the configuration of C-15 of the secologanin unit, using detailed NMR analysis, the configuration of C-3, the solution conformation around C-14, and the glucosidic bridge, as well as those of the dihydropyran and tetrahydropyridine rings, were determined in the vincosamide and strictosamide derivatives 4b and 5b. The stereochemical analysis was extended by chemical correlation to the 4-benzylated strictosidine and vincoside derivatives 3c and 3d. Experimental proof was presented for the interpretation of the 'anomalous' chemical shift of acetylated strictosamide derivatives.
- Patthy-Lukats, Agnes,Kocsis, Akos,Szabo, Laszlo F.,Podanyi
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p. 1492 - 1499
(2007/10/03)
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- Synthesis of four possible intermediates after secologanin on the biosynthesis of the oleoside-, 10-hydroxyoleoside- and ligustaloside-type glucosides in oleaceous plants
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To examine the biosynthetic pathways from secologanin to three types of secoiridoid glucosides characteristic of oleaceous plants, synthesis of two respective stereoisomers at C-8 of 8,10-epoxysecologanin and -secoxyloganin was established and their deuterium-labeled analogues were prepared.
- Kuwajima, Hiroshi,Tanahashi, Takao,Inoue, Kenichiro,Inouye, Hiroyuki
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p. 900 - 905
(2007/10/03)
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- Hydrolysis and Selective Reduction with Yeast: Enantiospecific Synthesis of Antirhine from Secologanin
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Glucoside hydrolysis and chemoselective reduction of secologanin ethylene acetal 2 with baker's yest affords a C-1 reduced aglucone 4 from which (+)-antirhine 8 is obtained in a four-step sequence.
- Brown, Richard T.,Dauda, Bukar E. N.,Santos, Cid A. M.
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p. 825 - 826
(2007/10/02)
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- BIOGENETICALLY PATTERNED SYNTHESIS OF CADAMBINE
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We report the synthesis of the glucosidic indole alkaloid cadambine (5) in 48 percent yield from its biological precursor secologanin (1) in an intermolecular variant of the in vivo process where chemoselective and regioselective attack by tryptamine on a 3S-epoxide 11 yields the seven-membered azepine ring.
- Brown, Richard T.,Duckworth, D. Malcolm,Santos, Cid A. M.
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p. 1987 - 1990
(2007/10/02)
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- Iridoids, XXI. - Synthesis of Secologanin
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Acid-catalyzed reaction of natural secologanin (1) with ethylene glycol to 5a, followed by acetylation gave the peracetylated acetal 5b in almost quantitative yield.Oxidation of 5b with equimolar or catalytic amounts of osmium tetraoxide afforded stereoselectively the diol 6 as main product (31percent resp. 28percent) besides recovered starting material. 5b was cleaved with lead tetraacetate to give 96percent of the aldehyde 10.Reaction of 10 with triphenylphosphonio-methanide led to the labelled secologanin derivative -5b and the pyran 12 in a 27percent and 52percent yield, respectively.Acid-catalyzed transacetalization of -5b to -5c, base-catalyzed solvolysis of the acetate groups to -5d and subsequent acid-catalyzed cleavage of the acetal gave secologanin (-1).To determine its configuration at C-9, 6 was transformed via 8a to the tricyclic system 8d, which was independently synthesized via a photocycloaddition of the galactose derivative 13 and diformylacetate 14.
- Tietze, Lutz F.,Henke, Stephan,Remberg, Gerd
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p. 1413 - 1427
(2007/10/02)
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- 245. Studies on Monoterpene Glucosides and Related Natural Products. Part 51. Absolute Structures of Hydrangenosides A, B, C, D, E, F, and G. Novel Type Secoiridoid Glucosides from Two Hydrangea Plants
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From Hydrangea macrophylla var. macrophylla, four new secoiridoid glucosides, hydrangenosides A, B, C and D, were isolated, along with the known iridoid glucosides loganin, secologanin, secologanic acid and sweroside.Moreover, hydrangenosides E, F, and G,
- Uesato, Shinici,Takeda, Yoshio,Hashimoto, Toshihiro,Uobe, Kenichi,Inouye, Hiroyuki,et al.
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p. 2111 - 2127
(2007/10/02)
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- THE CONVERSION OF SWEROSIDE TO SECOLOGANIN
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A chemical route from sweroside ( 2a ) to secologanin ( 1a ) has been established.The lactone ring of sweroside tetraacetate ( 2b ) was opened by trimethylsilyl iodide.The unstable iodo carboxylic acid 3 ( R=H; X=I ) was then formed and immediately converted to its methyl ester.The iodo function was displaced by formate, and the formate was selectively methanolized under neutral condotions.The resulting alcohol 3 ( R=Me; X=OH ) was oxidized by pyridinium chlorochromate to the aldehyde, secologanin teraacetate ( 1b ).With care, the conversion from the sweroside series to the secologanin series can be carried out in excellent yield.Secologanin can readily be recovered from its teraacetate.
- Hamilton, Raymond G.,McLean, Stewart
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p. 215 - 216
(2007/10/02)
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- SELECTIVE TRANSFORMATIONS OF SECOLOGANIN: DIHYDROXYLATION
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Sweroside tetraacetate ( 2b ) has been converted in high yield by osmylation to the epimeric glycols 3 and 4 ( R=H ) which have been separated.This reaction proceeds with high chemoselectivity for reaction at the vinyl side chain but with low stereoselectivity, leading to a small excess of the 3-R isomer.Secologanin derivatives appear to show a much lower chemoselectivity in this reaction, but the stereoselectivity is considerably higher, and opposite to that in the sweroside example.Conditions have been found for oxidizing the dimethylacetal 5b of secologanin tetraacetate in useful yields to the epimeric glycols 6 and 7 ( R=H ); in this reaction a large excess of the 3-S isomer is formed.The reasons for these differences in selectivity appear to be related to differences between the two series in conformational preference.
- Purdy, John Richard,Hamilton, Raymond G.,Akhter, Lalarukh,McLean, Stewart
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p. 210 - 214
(2007/10/02)
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