- Total syntheses of the non-peptide bradykinin B1 receptor antagonist velutinol a and its analogs, seco-pregnanes with a cage-like moiety
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We describe here the syntheses of velutinol A (1) and the structurally similar compounds 24 sharing a highly oxygenated seco-pregnane cage-like structure. The synthesis of velutinol A (1, 15,16-seco-pregnane) features the highly regioselective construction of |14 silyl enol ether from 15-keto-21,22-diol, followed by stereoselective introduction of a sterically hindered β-hydroxy group at the C14 position by Rubottom oxidation. Prolonged reaction time and the use of an excess amount of mCPBA at this step allowed double Rubottom oxidation, enabling us to introduce the requisite hydroxy groups at the C14 and C16 positions in one pot. Subsequent oxidative cleavage of the C1516 bond, deprotection, and intramolecular acetalization allowed the concise total synthesis of velutinol A (1). Utilization of α,α-dihydroxy-ketone, the double Rubottom oxidation product, for formation of the ether F-ring by 5-exo-cyclization, and subsequent C1421 oxidative cleavage, effectively achieved the synthesis of pentalinonside-aglycon (2). Construction of the 14,15-seco-structures of two other analogs, argeloside aglycon (3) and illustrol (4), was achieved by BaeyerVilliger oxidation of 15(21)-keto derivatives. Introduction of the 20-oxo group potentially embedded in argeloside aglycon was accomplished by Wacker oxidation of |20, which was constructed by GriecoNishizawa syn-β-elimination of the C21-primary alcohol obtained by reduction of the BaeyerVilliger product. Intra-molecular double acetalization of the 15,16-dihydroxy-14,20-oxo derivative to form the cage-like structure of the DEF-rings required a moderately weak acid. This step was the key to accessing argeloside aglycon (3), as otherwise the easily aromatized β,γ-dihydroxyketone moiety was transformed to furan. Sharpless asymmetric dihydroxylation of |20 to set the C20 stereocenter, followed by intramolecular double acetalization, achieved the stereoselective synthesis of illustrol With all synthesized compounds, structural requirements of steroidal bradykinine B1 receptor antagonist would be revealed.
- Tamiya, Minoru,Isaka, Nobuhisa,Kitazawa, Takaaki,Hasegawa, Atsushi,Ishizawa, Kazuya,Ikeda, Mayu,Kawada, Saki,Ishiguro, Masaji
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supporting information
p. 1474 - 1494
(2019/09/30)
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- Efficient Two-Step Multifunctionalization of Substituted 2-Hydro-xyglycopyranosides
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A straightforward route to diversely functionalized glycopyranosides is reported. 2,3-Enopyranosides, 2- and/or 3-azido-, 2-halopyranosides, and a hex-3-ulose, among other α- and β-glycopyranosides are easily obtained in good to excellent yields from 2-hydroxyglycopyranosides by means of a two-step process involving trifluoromethanesulfonation and subsequent treatment with the appropriate nucleophilic agent.
- Franconetti, Antonio,álvarez, Eleuterio,Cabrera-Escribano, Francisca
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p. 201 - 206
(2017/01/25)
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- Base-promoted reaction of methyl 4,6-O-benzylidene-3-deoxy-hexopyranosid-2- ulose and various arylamines
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Reaction of methyl 4,6-O-benzylidene-3(2)-deoxy-hexopyranosid-2(3)-ulose (1) with various arylamines under Bargellini reaction conditions was investigated. A series of unique enaminoketones 3-12 was obtained unexpectedly under basic conditions in 52-72% y
- Sun, Jun,Zhang, Xuefeng,Li, Fulong,Ding, Chunyong,Wu, Wenjuan,Zhang, Ao
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supporting information; experimental part
p. 5693 - 5696
(2011/11/04)
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- New mannose-derived ketones as organocatalysts for enantioselective dioxirane-mediated epoxidation of arylalkenes. Part 3: Chiral ketones from sugars
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New d-arabino-hexopyranosid-3-uloses were synthesized by a simple method from mannopyranoside derivatives. The common skeleton possesses a tunable alkoxy group as steric sensor on carbon 2 of the sugar. The new ketones were employed in the dioxirane-mediated epoxidation of a range of trans- and trisubstituted arylalkenes giving enantiomeric excesses from low to good (30-90%). The effect of the size of the steric sensor on the enantioselectivity was also studied. The least bulky group (methoxy group) enhanced the stereoselectivity (up to 90% ee toward triphenylethylene).
- Vega-Pérez, José M.,Peri?án, Ignacio,Vega-Holm, Margarita,Palo-Nieto, Carlos,Iglesias-Guerra, Fernando
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p. 7057 - 7065
(2011/10/05)
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- Synthesis of annelated pyranosides: a rapid and efficient entry to highly functionalized optically pure branched-pyrazoles
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Pyrazolo-pyranosides prepared from methyl-2,3:4,6-di-O-benzylidene-α-d-mannopyranoside were functionalized to design new scaffolds suitable for peptidomimetic construction. Under certain acidic conditions, they undergo only pyranose ring-opening generatin
- Samb, Issa,Pellegrini-Mo?se, Nadia,Chapleur, Yves
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p. 7978 - 7981
(2008/03/14)
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- m-iodosylbenzoic acid as a convenient recyclable reagent for highly efficient RuCl3-catalyzed oxidation of alcohols to carbonyl compounds
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m-Iodosylbenzoic acid selectively oxidizes primary and secondary alcohols to the respective carbonyl compounds in the presence of RuCl3 (0.5 mol%) at room temperature in aqueous acetonitrile. Separation of pure products is conveniently achieved by scavenging any aryl iodide by ion exchange with IRA-900 (hydroxide form) or by simple extraction of the basic aqueous solution with water. The reduced form of the reagent, m-iodobenzoic acid, can be easily recovered from the ion-exchange resin or from the basic aqueous solution by simple acidification with HCl. Georg Thieme Verlag Stuttgart.
- Yusubov, Mekhman S.,Gilmkhanova, Marina P.,Zhdankin, Viktor V.,Kirschning, Andreas
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p. 563 - 566
(2007/10/03)
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- Tagged hypervalent iodine reagents: A new purification concept based on ion exchange through SN2 substitution
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(Chemical Equation Presented) The preparation of phenylsulfonate-tagged iodine(III) reagents as well as their use in a novel purification strategy for iodine(III)-promoted reactions is described. The concept is based on ion exchange and is initiated by an azide-promoted SN2-reaction at the alkyl sulfonate followed by trapping of the resulting aryl sulfonate anion with an ion-exchange resin. The concept is successfully proven for Ru-catalyzed oxidations of alcohols, the activation and glycosidatlon of thioglycosides, and the Suarez reaction of pyranoses.
- Kunst, Eike,Gallier, Florian,Dujardin, Gilles,Yusubov, Mekhman S.,Kirschning, Andreas
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p. 5199 - 5202
(2008/09/17)
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- Enantioselective formal total synthesis of the antitumor macrolide bryostatin 7
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A new enantioselective synthesis of Masamune's AB fragment (1) for bryostatin 7 is described. Key steps in the new route include a Meerwein-Ponndorf-Verley reduction to set the 0(7) stereocenter and an alkylative union between the dithiane 6 and iodide 5 to construct the C(9)-C(10) bond. Because we have previously published a synthesis of Masamune's C-ring phenyl sulfone 2, our new route to 1 constitutes a formal total synthesis of bryostatin 7; it also corrects the previously reported spectral data for 1 in CDCl3.
- Manaviazar, Soraya,Frigerio, Mark,Bhatia, Gurpreet S.,Hummersone, Marc G.,Aliev, Abil E.,Hale, Karl J.
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p. 4477 - 4480
(2007/10/03)
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- Synthesis of L-vancosamine derivatives from methyl α-D- mannopyranoside
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Concise synthesis of L-vancosamine, the amino sugar constituent of vancomycin and other antibiotics, has been achieved. The key steps include (1) stereoselective addition of methylcerium reagent to oximino ether, and (2) stereoselective hydrogenation of 5
- Hsu, Day-Shin,Matsumoto, Takashi,Suzuki, Keisuke
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p. 469 - 471
(2007/10/03)
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- A simple and mild synthesis of a 4,5-cyclopropanated carbohydrate
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The synthesis of a 4,5-cyclopropanated carbohydrate was achieved in five steps from methyl α-d-mannopyranoside under mild conditions that avoid the use of carbene chemistry.
- Testero, Sebastian A.,Spanevello, Rolando A.
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p. 1057 - 1060
(2007/10/03)
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- Practical TEMPO-mediated oxidation of alcohols using different polymer-bound co-oxidants
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Hypochlorite and chlorite exchange resins are evaluated as co-oxidants or oxidants, respectively, for the oxidation of alcohols to the corresponding aldehydes, ketones or carboxylic acids. Polymer-bound hypochlorite can act as a co-oxidant in TEMPO-mediated oxidations of alcohols. The formation of aldehydes only works under weakly acidic conditions. However, the cheap hypochlorite exchange resin is less efficient as co-oxidant compared to the use of ionically immobilised bisacetoxybromate(I) anions. In contrast, the chlorite exchange resin is a highly potent co-oxidant for the preparation of carboxylic acids from the corresponding primary alcohols in the presence of TEMPO. It is demonstrated that in this case also the resin acts as a polymer-bound co-oxidant for both oxidation steps. Yields are commonly excellent as is also demonstrated for examples taken from natural product synthesis which include acid labile glycosides. In most cases, work-up of this heavy metal-free oxidation is kept to a minimum. It often includes filtration followed by removal of the solvent.
- Kloth, Katrin,Bruenjes, Marco,Kunst, Eike,Joege, Thomas,Gallier, Florian,Adibekian, Alexander,Kirschning, Andreas
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p. 1423 - 1434
(2007/10/03)
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- Synthesis of N-acylated 7-amino-2,6,7-trideoxy-D-erythroheptopyranosides from methyl α-D-mannoside
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Hexopyranoside methyl α-d-mannoside (8) was homologated to yield 7-(acylamino)-2,6,7-trideoxy-heptopyranosides 19-26. A crucial reaction step is the radical cleavage of benzylidene derivative 10 to obtain bromide 11. Since nucleophilic substitution of 11
- Wiedemeyer, Kathrin,Wuensch, Bernhard
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p. 2483 - 2493
(2007/10/03)
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- Synthesis of D-rubranitrose by using a novel method for constructing functionalized branched-chain structures
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Convenient synthesis of D-rubranitrose from D-glucose was achieved by using simple and novel methods for deoxygenation and construction of functionalized branched-chain structures. The total yield of D-rubranitrose from methyl 4,6-O-benzylidene-α-D-glucop
- Sato, Ken-Ichi,Miyama, Daisuke,Akai, Shoji
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p. 1523 - 1525
(2007/10/03)
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- The synthesis of some deoxygenated analogues of early intermediates in the biosynthesis of glycosylphosphatidylinositol (GPI) membrane anchors
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Syntheses are described of 2-azido-4,6-di-O-benzyl-2,3-dideoxy-D-ribo- hexopyranosyl fluoride, 6-O-acetyl-2-azido-3-O-benzyl-2,4-dideoxy-D-xylo- hexopyranosyl fluoride and 2-azido-3,4-di-O-benzyl-2,6-dideoxy-D-glucopyranosyl fluoride. These glycosyl donor
- Dix, Alexander P.,Borissow, Charles N.,Ferguson, Michael A. J.,Brimacombe, John S.
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p. 1263 - 1277
(2007/10/03)
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- Stereoselective entry to β-linked C-disaccharides using a carbon-ferrier reaction
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(Matrix presented) The synthesis of unsaturated β-linked C-disaccharides by the Lewis acid-mediated reaction of 3-O-acetylated glycals with monosaccharide-derived alkenes is described. Deprotection and selective hydrogenation of an exocyclic carbon-carbon
- Gemmell, Natasha,Meo, Paul,Osborn, Helen M. I.
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p. 1649 - 1652
(2007/10/03)
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- Studies of the stereoselective reduction of ketosugar (hexosulose)
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The results from the studies of the stereoselective reduction of ketosugar (hexosulose) were reported. Combining our results and those reported in the literature, we summarize the factors in controlling the stereoselective reduction of ketosugars. These findings are valuable in the synthesis of various carbohydrate derivatives.
- Chang, Cheng-Wei Tom,Hui, Yu,Elchert, Bryan
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p. 7019 - 7023
(2007/10/03)
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- Total synthesis of soraphen A(1α)
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The convergent synthesis of macrolide soraphen A(1α) is described starting from glucose (western part) and mannose (eastern part). Mannose was converted into a 2-deoxyribohexopyranoside that could be methylated and reduced stereoselectively. Chain elongation at C-6 was carried out by stereoselective addition of a magnesium acctylide. The two fragments (western and eastern) were assembled by a Julia olefination followed by macrolactonization. The introduction of the methyl group at C-2 of norsoraphen occurred stereoselectively for thermodynamic reasons.
- Abel, Stephan,Faber, Dominik,Hueter, Ottmar,Giese, Bernd
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p. 188 - 197
(2007/10/03)
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- Synthesis of homochiral trisubstituted γ-butyrolactones
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Efficient syntheses of homochiral, trisubstituted γ-butyrolactones via the highly stereoselective alkylation of a carbohydrate-derived γ-lactone are described.
- Alker,Jones,Taylor,Wood
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p. 1667 - 1670
(2007/10/02)
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- O- and C-Acylation of some Carbohydrate Enolates
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The enolate derived from methyl 4,6-O-benzylidene-2-deoxy-α-D-erythro-hexopyranosid-3-ulose undergoes O-acylation exclusively with a variety of reagents, whereas C-acylation is successful only with the corresponding C-glycosyl derivatives.
- Tsang, Raymond,Fraser-Reid, Bert
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- Synthesis of L-Daunosamine
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A convenient and inexpensive preparation of methyl 4,6-O-benzylidene-2-deoxy-α-D-erythrohexopyranosid-3-ulose (2), an important intermediate for the synthesis of L-daunosamine (1) is described.
- Gurjar, M. K.,Yadav, J. S.,Rama Rao, A. V.
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p. 1139 - 1140
(2007/10/02)
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- New Ketone Synthesis via β-Hydroxy o-Nitrophenyl Selenoxides; a One-step Synthesis of Deoxy-keto Sugars
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β-Hydroxy o-nitrophenyl selenides and their O-alkyl or O-acyl derivatives were prepared and converted into ketones or the corresponding enol derivatives in satisfactory yields; these reactions were applied to the synthesis of sugar derivatives.
- Furuichi, Kimiaki,Yogai, Sadamu,Miwa, Toshio
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