- Rhodium-catalysed vinyl 1,4-conjugate addition coupled with Sharpless asymmetric dihydroxylation in the synthesis of the CDE ring fragment of pectenotoxin-4
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Our synthesis of the CDE ring fragment of pectenotoxin-4 utilised two key steps to make the complex bicyclic ketal unit: (i) a rhodium-catalysed vinyl group 1,4-addition as the major C-C bond forming step; (ii) a stereoselective Sharpless Asymmetric Dihydroxylation (SAD) of the resulting 1,1-disubstituted homoallylic alcohol. Subsequent acid-catalysed cyclisation afforded the desired [5,6]-bicyclic ketal of the target molecule. This methodology was shown to be compatible with the desired E ring fragment 35 in order to construct the CDE fragment 37 of pectenotoxin-4.
- Richardson, Melodie S. W.,Tame, Christopher J.,Poole, Darren L.,Donohoe, Timothy J.
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p. 6336 - 6340
(2019/07/04)
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- Effective and one-step stereo-controlled synthesis of benzyloxylated- diiodopentanes for the synthesis of five-membered imino-sugars
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An effective and stereo-controlled synthesis of 1,3,4-tris(benzyloxy)-2,5- diiodopentane starting from 2,3,5-tris(benzyloxy)pentane-1,4-diol was reported. Synthesis was improved to get the diiodide compound instead of forming the ring-closure product (ben
- Guo, Lina,Liu, Yonghui,Wan, Yue,Wang, Peng George,Zhao, Wei
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p. 2579 - 2582
(2013/06/26)
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- Synthesis and biological properties of chemically modified siRNAs bearing 1-deoxy-d-ribofuranose in their 3′-overhang region
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To elucidate the role of the sugar moiety in the two natural nucleotides of the 3′-overhang region of small interfering RNA (siRNA), we synthesized siRNAs that incorporated two abasic nucleosides, 1-deoxy-d-ribofuranose (R H). We improved the method for preparing an O-protected abasic nucleoside, 1-deoxy-2,3,5-tri-O-benzoyl-β-d-ribofuranose, via the reductive cleavage of the anomeric position of 1-O-acetyl-2,3,5-tri-O-benzoyl-β-d- ribofuranose. To incorporate RH into oligonucleotides by the standard phosphoramidite solid phase method, RH was converted into its phosphoramidite derivative and the solid support linked to a controlled pore glass resin. Chemically modified RNAs possessing RH at the 3′-overhang region were easily prepared in good yields. siRNAs containing RH showed moderate nuclease-resistance and a desirable knockdown effect.
- Taniho, Kazumi,Nakashima, Remi,Kandeel, Mahmoud,Kitamura, Yoshiaki,Kitade, Yukio
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supporting information; experimental part
p. 2518 - 2521
(2012/05/20)
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- Lewis acid catalyzed ring-opening reactions of sugar-derived semicyclic N,O-acetals
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N-(Alkoxycarbonyl)-N-glycosides (polyoxygenated semicyclic N.O-acetals) were efficiently synthesized from regular acetyl or methyl glycosides (glucopyranoside, ribofuranoside, arabinofuranoside, and 2-deoxyribofuranoside) and a carbamate by treatment of t
- Sugiura, Masaharu,Hagio, Hiroyuki,Kobayashi, Shu
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p. 3678 - 3691
(2007/10/03)
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- Synthesis of fluorobenzene and benzimidazole nucleic-acid analogues and their influence on stability of RNA duplexes
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Six different ribonucleoside phosphoramidites with fluorobenzenes or fluorobenzimidazoles as base analogues, one abasic site, and inosine were synthesized and incorporated into oligoribonucleotides. The oligomers were investigated by means of UV and CD spectroscopy to assess the contribution of H-bonding, base stacking, and solvation to the stability of the RNA duplex. CD Spectra show that the incorporation of modified nucleosides does not lead to changes in the structure of RNA. The T(m) differences determined are based on changes in base stacking and solvation. Individual contributions of base stacking and solvation of the modified nucleosides could be determined. In fluorobenzene·fluorobenzimidazole-modified base pairs, a duplex-stabilizing force was found that points to a weak F ··· H H-bond.
- Parsch, Joerg,Engels, Joachim W.
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p. 1791 - 1808
(2007/10/03)
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- Synthetic utility of 1,1,2,2-tetraaryIdisilanes: Radical reduction of alkyl phenyl chalcogenides
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Reactivity of tetraaryldisilanes as radical reducing agents of alkyl phenyl chalcogenides initiated by Et3B or AIBN was studied. Here, the reactivity of alkyl sulfide was poor; however, various alkyl phenyl selenides and tellurides were reduced to the corresponding hydrocarbons in good yields with 1,1,2,2-tetraphenyldisilane. The Royal Society of Chemistry 1999.
- Yamazaki, Osamu,Togo, Hidco,Yokoyama, Masataka
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p. 2891 - 2896
(2007/10/03)
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- Facile synthesis of 3'-C-branched 1,5-anhydrohexitol nucleosides
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The 3'-β-C-branched anhydrohexitol nucleosides have been conveniently synthesised starting from commercially available D-ribose following the reaction sequence: (i) conversion of protected pentofuranose sugar to the corresponding hexopyranosyl nitrosugar (ii) addition of the conjugate base of nitrosugar to formaldehyde to obtain C-branched nitro sugar (iii) removal of nitro group by n-tributyltin hydride treatment and (iv) Mitsunobu type alkylation to build up the nucleobase.
- Hossain, Nafizal,Herdewijn, Piet
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p. 1781 - 1786
(2007/10/03)
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- Synthesis of 3'-C-branched 1',5'-anhydromannitol nucleosides as new antiherpes agents
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A series of 3'-β-C-branched anhydromannitol nucleosides were conveniently synthesized starting from commercially available D-ribose. The reaction sequences were: (i) conversion of the protected pentofluranose to the corresponding nitrohexopyranose; (ii) addition of the conjugated base of the nitrosugar to formaldehyde; (iii) removal of the nitro group by n-tributyltin hydride treatment and (iv) Mitsunobu type alkylation to introduce the nucleobase. The conformation of intermediates and final compounds were deduced from NMR analysis. The thymine congener showed potent activity against herpes simplex virus (HSV).
- Hossain, Nafizal,Van Halbeek, Herman,De Clercq, Erik,Herdewijn, Piet
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p. 2209 - 2226
(2007/10/03)
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- Samariumdiiodid-vermittelte Kupplung von Glycosylphosphaten mit Kohlenstoffradikal- oder -anion-Acceptoren - Synthese von C-Glycosiden
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Keywords: C-Glycoside; Verknuepfungen; Samariumverbindungen; Synthesemethoden
- Hung, Shang-Cheng,Wong, Chi-Huey
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p. 2829 - 2832
(2007/10/03)
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- Synthesis of isonucleosides related to AZT and AZU
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Approaches to 1,4-anhydro-3-azido-2,3-dideoxy-2-[3,4-dihydro-2,4-dioxo-5- methyl-1(2H)-pyrimidinyl]-D-arabinitol, and the related uracil derivative, have been developed. These conceptually new, optically active analogs of AZT, derived from 1,4-anhydro-D-ribitol, are among the first examples of regioisomeric analogs of AZT.
- Purdy,Zintek,Nair
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p. 109 - 126
(2007/10/02)
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- The Preparation of Dioxaprostacyclin Analogues from D-(-)-Ribose
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Using D-(-)-ribose as chiral starting material, we have prepared 1-deoxy-D-ribofuranose by a novel route, and then employed both compounds as precursors of the dioxaprostacyclin analogues (2).
- Heath, Peter,Mann, John,Walsh, E. Brian,Wadsworth, Alan H.
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p. 2675 - 2679
(2007/10/02)
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