Reactions of nitro sugars. XII. A novel type of disaccharide synthesis

1969 ◽  
Vol 47 (15) ◽  
pp. 2819-2826 ◽  
Author(s):  
Hans H. Baer ◽  
Frank Kienzle
Keyword(s):  
Ethylenic Bond ◽  
Hydroxyl Group ◽  
Reaction Conditions ◽  
Free Hydroxyl ◽  
Sugar Derivatives ◽  
Derivatives Of

Nitro disaccharide methyl glycosides were obtained by base-catalyzed addition of partially blocked sugar derivatives having one free hydroxyl group, across the ethylenic bond in methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-β-D-erythro-hex-2-enopyranoside (1) and its α-anomer (2). Thus, the addition of 2,3,4,6-tetra-O-acetyl-β-D-glucopyranose (3) gave blocked derivatives of sophorose, namely methyl 2-O-(2,3,4,6-tetra-O-acetyl-β-D-glucopyranosyl)-4,6-O-benzylidene-3-deoxy-3-nitro-β-D-glucopyranoside (4) and -α-D-glucopyranoside (5). Similarly, the use of methyl 4,6-O-benzylidene-3-deoxy-3-nitro-β-D-glucopyranoside (10) and its α-anomer (13) as addends led to 2 → 2 linked bisglycosidyl ethers; these were the methyl 4,6-O-benzylidene-3-deoxy-2-O-(methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-D-gluco-pyranosid-2-yl)-3-nitro-D-glucopyranosides with the anomeric configurations β,β, α,α, and α,β (11, 14, and 15, respectively). Methyl 4,6-O-benzylidene-3-deoxy-3-nitro-β-D-mannopyranoside (12) was found to epimerize to 10 under the reaction conditions; therefore, interaction of 12 and 1 also gave the bis-β-D-glucosidyl ether (11). The L-enantiomer of 12 gave with 1 an optically inactive meso compound (16) possessing a β-L- and a β-D-glucosidyl moiety.

Phosphonylmethoxyalkyl and phosphonylalkyl derivatives of adenine

1988 ◽  
Vol 53 (11) ◽  
pp. 2753-2777 ◽  
Author(s):  
Ivan Rosenberg ◽  
Antonín Holý ◽  
Milena Masojídková
Keyword(s):  
Sodium Periodate ◽  
Alkyl Chain ◽  
Alkaline Treatment ◽  
Hydroxyl Group ◽  
Dialkyl Phosphite ◽  
Analogous Reaction ◽  
Trialkyl Phosphite ◽  
Free Hydroxyl ◽  
Subsequent Cyclization ◽  
Derivatives Of

Analogues of the antivirals (2S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (Ia) and 9-(2-phosphonylmethoxyethyl)adenine (Ib), modified in the alkyl chain, are described. The phosphonylmethoxyalkyl derivatives were prepared by condensation of sodium alkoxides of hydroxyalkyladenines (or their N-protected derivatives) with dimethyl p-toluenesulfonyloxymethanephosphonate (II) followed by alkaline hydrolysis and reactions with halotrimethylsilane, or by reaction of vicinal dihydroxyalkyl derivatives with chloromethanephosphonyl dichloride (XIV) and subsequent cyclization of the intermediates XV in aqueous alkali. In the second case the pure regioisomers were also obtained from substituted dihydroxy derivatives with one free hydroxyl group. The following compounds were prepared in this way: 3-O-methyl ether IIIc and 3-O-octyl ether IVc, 9-(3-phosphonylmethoxypropyl)- (Vc), 9-(4-phosphonylmethoxybutyl)- (Vf), 9-(5-phosphonylmethoxypentyl)- (Vi), 9-(2-phosphonylmethoxypropyl)- (VIc), 9-(1-phosphonylmethoxy-3-hydroxy-2-propyl)- (XIIc), 9-(2-methoxy-3-phosphonylmethoxypropyl)- (XIIIc), erythro-9-(2-phosphonylmethoxy-3,4-dihydroxybutyl)- (VIIc) and threo-9-(4-phosphonylmethoxy-2,3-dihydroxybutyl)adenine (IXc) and its enantiomer (Xc). 9-(2-Phosphonylmethoxy-3,3-dihydroxypropyl)adenine (VIII) was obtained by oxidation of VIIc with sodium periodate, 9-(2-phosphonylmethoxyethoxymethyl)adenine (XIc) by reaction of II with sodium salt of 9-(2-hydroxyethoxymethyl)adenine (XIa). 9-(1,2-Dihydroxy-2-methyl-3-propyl)adenine 1- and 2-phosphonylmethyl ether (XVIb), 9-(3,4-dihydroxybutyl)adenine 3- and 4-phosphonylmethyl ether (XVIIb) and 9-(2,3-dihydroxybutyl)adenine 2- and 3-phosphonylmethyl ether (XVIIIb) were prepared by reaction with chloromethanephosphonyl dichloride (XIV) followed by alkaline treatment. Analogous reaction was also employed in the preparation of regioisomerically pure 1-phosphonylmethyl ethers of 9-(1,2-dihydroxy-3-butyl)adenine (XXIV), 9-(1,2-dihydroxy-2-methyl-3-propyl)adenine (XVIb) and 9-(1,2-dihydroxy-3-nonyl)adenine (XXV). Alkylation of adenine with diethyl chloromethoxymethanephosphonate (XXVII) followed by hydrolysis afforded 9-(phosphonylmethoxymethyl)adenine (XXVIIIb). 9-(Phosphonylmethyl)adenine (XLI) was obtained by condensation of adenine with compound II. Conversion of 9-(ω-hydroxyalkyl)adenines into the ω-halogenoalkyl derivatives followed by reaction with trialkyl phosphite and cleavage was used in the preparation of 9-(2-phosphonylethyl)adenine (XXXIVa), 9-(4-phosphonylbutyl)adenine (XXXIVb) and 9-(2-phosphonylethoxymethyl)adenine (XXXIX). 9-(2-Phosphonyl-2-hydroxyethyl)adenine (Lc) and 9-(3-phosphonyl-3-hydroxypropyl)adenine (Lb) were synthesized by treatment of ω-(adenin-9-yl)alkanals with dialkyl phosphite and subsequent cleavage with halogenotrimethylsilane; the same procedure converted 9-(2-oxopropyl)adenine (XLVIIIa) into 9-(2-phosphonyl-2-hydroxypropyl)adenine (La).

scholarly journals Optimization of Reactions Opening Cyclic Ring of Pentose Sugar Derivatives through Dithioacetalisation Reactions

2017 ◽  
Vol 17 (2) ◽  
pp. 79
Author(s):  
Nuriman Nuriman
Keyword(s):  
Reaction Time ◽  
Ring Opening ◽  
Solvent Mixture ◽  
Reaction Products ◽  
Reaction Conditions ◽  
Ring Opening Reaction ◽  
Pentose Sugar ◽  
Sugar Derivatives ◽  
Derivatives Of ◽  
Better Than

Ring-opening reaction of cyclic pentose sugar derivatives of 2,3,4-Tri-O-benzyl- D-xylopyranoseto derivatives of acyclic 2,3,4-Tri-O-benzyl-D-xylose-Dipropyl dithioacetal been done andoptimized. The reaction was performed using a precursor propanathiol with concentrated HCl.Optimization of reaction conditions was conducted by varying propanathiol concentration,reaction time and optimization of the reaction temperature which the product ioslation conductedusing a variety of solvents. The results of this reaction was obtained 2,3,4-Tri-O-benzyl- Dxylose-Dipropyl dithioacetal with the highest randemen (97%), better than the previous reactionthrough propanathiol excessive concentration, reaction time of 2 hours and the temperature of thereaction at room temperature. Product Isolations using solvent dikloromathane more effectivethan the use of other organic solvents. Purification of reaction products is done through a columnchromatography using a solvent mixture of 20% ethyl acetate-hexane.Keywords: Optimization, Cyclic Ring, Dithioasetalisasi 

Inductive effect in EI-mass spectra of some 5,6-dihalogenides and 5,6-halohydrins of 5α-cholestan-3β-ol and 3β-acetoxy-5α-cholestane

1982 ◽  
Vol 47 (11) ◽  
pp. 2946-2960 ◽  
Author(s):  
Antonín Trka ◽  
Alexander Kasal
Keyword(s):  
Mass Spectra ◽  
Inductive Effect ◽  
Molecular Ions ◽  
Hydroxyl Group ◽  
Halogen Atoms ◽  
Derivatives Of

Partial EI-mass spectra of 3β-hydroxy- and 3β-acetoxy-5α-cholestanes substituted in positions 5α-, 6β- or 5α,6β- with a hydroxyl group or halogen atoms (fluorine, chlorine, bromine) are presented. The molecular ions of 5α,6β-disubstituted derivatives of 3β-hydroxy-5α-cholestane (or of its 3-acetate) are considerably more stable than the corresponding monosubstituted derivatives if at least one of the pair of the vicinal substituents is chlorine or fluorine. This increase in stability, most striking in 5α- and 6β-fluoro compounds, is explained by the inductive effect.

Cleavage of the Epimines of 1,6-Anhydrohexoses with Fluoride Anion

2005 ◽  
Vol 70 (12) ◽  
pp. 2075-2085 ◽  
Author(s):  
Jiří Kroutil ◽  
Klára Jeništová
Keyword(s):  
Fluoride Anion ◽  
Ring Cleavage ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Aziridine Ring ◽  
Cleavage Reactions ◽  
Derivatives Of ◽  
Fluoro Derivatives

Aziridine ring cleavage reactions of five N-nosylepimines (2-6) having D-talo, D-galacto, D-manno, and D-allo configurations with potassium hydrogendifluoride under various reaction conditions have been performed. The cleavage regioselectively afforded diaxial isomers of vicinal amino-fluoro derivatives of 1,6-anhydro-β-D-gluco- and mannopyranose 7-11 in 51-94% yields. Removal of 2-nitrobenzenesulfonyl protecting group with benzenethiol has been attempted in the case of compound 10.

scholarly journals Enzymatic synthesis and phosphorolysis of 4(2)-thioxo- and 6(5)-azapyrimidine nucleosides by E. coli nucleoside phosphorylases

2016 ◽  
Vol 12 ◽  
pp. 2588-2601 ◽  
Author(s):  
Vladimir A Stepchenko ◽  
Anatoly I Miroshnikov ◽  
Frank Seela ◽  
Igor A Mikhailopulo
Keyword(s):  
Purine Nucleoside Phosphorylase ◽  
Reaction Conditions ◽  
E Coli ◽  
No Formation ◽  
Structural Peculiarities ◽  
Substrate Properties ◽  
Nucleoside Phosphorylases ◽  
Derivatives Of

The trans-2-deoxyribosylation of 4-thiouracil (4SUra) and 2-thiouracil (2SUra), as well as 6-azauracil, 6-azathymine and 6-aza-2-thiothymine was studied using dG and E. coli purine nucleoside phosphorylase (PNP) for the in situ generation of 2-deoxy-α-D-ribofuranose-1-phosphate (dRib-1P) followed by its coupling with the bases catalyzed by either E. coli thymidine (TP) or uridine (UP) phosphorylases. 4SUra revealed satisfactory substrate activity for UP and, unexpectedly, complete inertness for TP; no formation of 2’-deoxy-2-thiouridine (2SUd) was observed under analogous reaction conditions in the presence of UP and TP. On the contrary, 2SU, 2SUd, 4STd and 2STd are good substrates for both UP and TP; moreover, 2SU, 4STd and 2’-deoxy-5-azacytidine (Decitabine) are substrates for PNP and the phosphorolysis of the latter is reversible. Condensation of 2SUra and 5-azacytosine with dRib-1P (Ba salt) catalyzed by the accordant UP and PNP in Tris∙HCl buffer gave 2SUd and 2’-deoxy-5-azacytidine in 27% and 15% yields, respectively. 6-Azauracil and 6-azathymine showed good substrate properties for both TP and UP, whereas only TP recognizes 2-thio-6-azathymine as a substrate. 5-Phenyl and 5-tert-butyl derivatives of 6-azauracil and its 2-thioxo derivative were tested as substrates for UP and TP, and only 5-phenyl- and 5-tert-butyl-6-azauracils displayed very low substrate activity. The role of structural peculiarities and electronic properties in the substrate recognition by E. coli nucleoside phosphorylases is discussed.

scholarly journals Studies on the formation of complex oxidation and condensation products of phenols. Part III. -Rearrangements of oxidation-reduction type in the diquinone group

1933 ◽  
Vol 143 (848) ◽  
pp. 223-228 ◽  
Keyword(s):  
Hydroxyl Group ◽  
Hydrogen Atoms ◽  
Blue Colour ◽  
Highly Active ◽  
Oxidation Reduction ◽  
Intramolecular Reactions ◽  
Trimethyl Ether ◽  
Free Hydroxyl ◽  
Ethereal Oxygen ◽  
Complex Oxidation

The diquinones have been but little investigated, and as they contain two condensed highly active quinonid systems it is to be anticipated that they should be capable of interesting intramolecular reactions. When heated to 210-215º, 4 : 4'-dimethoxydiquinone is rapidly converted into a red crystalline isomeride (yield, 90%), soluble in alkali with an intense blue colour, and yielding a mono-acetate indicating the occurrence of a free hydroxyl group. Two hydrogen atoms are taken up on reduction, and the phenolic product yields a triacetate and a trimethyl ether. It follows that of the four carbonyl oxygens of 4 : 4'-dimethoxydiquinone, one has been converted into a hydroxyl group, and another which does not exhibit any functional activity, is probably present as ethereal oxygen. These results led to formula (III) as representing the product of rearrangement.

scholarly journals Intramolecular Nitrile Oxide—Alkene Cycloaddition of Sugar Derivatives with Unmasked Hydroxyl Group(s).

ChemInform ◽  
2007 ◽  
Vol 38 (29) ◽  
Author(s):  
Tony K. M. Shing ◽  
Wai F. Wong ◽  
Hau M. Cheng ◽  
Wun S. Kwok ◽  
King H. So
Keyword(s):  
Nitrile Oxide ◽  
Hydroxyl Group ◽  
Sugar Derivatives

The syntheses of 6-C-alkyl derivatives of methyl α-isomaltoside for a study of the mechanism of hydrolysis by amyloglucosidase

2001 ◽  
Vol 79 (2) ◽  
pp. 238-255 ◽  
Author(s):  
Ulrike Spohr ◽  
Nghia Le ◽  
Chang-Chun Ling ◽  
Raymond U Lemieux
Keyword(s):  
Hydrogen Bonds ◽  
Molecular Model ◽  
Aromatic Amino Acids ◽  
Hydroxyl Group ◽  
Bulk Solution ◽  
Anomeric Effect ◽  
Nmr Studies ◽  
Intermolecular Hydrogen Bonds ◽  
Model Calculations ◽  
Derivatives Of

The epimeric (6aR)- and (6aS)-C-alkyl (methyl, ethyl and isopropyl) derivatives of methyl α-isomaltoside (1) were synthesized in order to examine the effects of introducing alkyl groups of increasing bulk on the rate of catalysis for the hydrolysis of the interunit α-glycosidic bond by the enzyme amyloglucosidase, EC 3.2.1.3, commonly termed glucoamylase (AMG). It was previously established that methyl (6aR)-C-methyl α-isomaltoside is hydrolysed about 2 times faster than methyl α-isomaltoside and about 8 times faster than its S-isomer. The kinetics for the hydrolyses of the ethyl and isopropyl analogs were also recently published. As was expected from molecular model calculations, all the R-epimers are good substrates. A rationale is presented for the catalysis based on conventional mechanistic theories that includes the assistance for the decomposition of the activated complex to products by the presence of a hydrogen bond, which connects the 4a-hydroxyl group to the tryptophane and arginine units. It is proposed that activation of the initially formed complex to the transition state is assisted by the energy released as a result of both of the displacement of perturbed water molecules of hydration at the surfaces of both the polyamphiphilic substrate and the combining site and the establishment of intermolecular hydrogen bonds, i.e., micro-thermodynamics. The dissipation of the heat to the bulk solution is impeded by a shell of aromatic amino acids that surround the combining site. Such shields are known to be located around the combining sites of lectins and carbohydrate specific antibodies and are considered necessary to prevent the disruption of the intermolecular hydrogen bonds, which are of key importance for the stability of the complex. These features together with the exquisite stereoelectronic dispositions of the reacting molecules within the combining site offer a rationalization for the catalysis at ambient temperatures and near neutral pH. The syntheses involved the addition of alkyl Grignard reagents to methyl 6-aldehydo-α-D-glucopyranoside. The addition favoured formation of the S-epimers by over 90%. Useful amounts of the active R-isomers were obtained by epimerization of the chiral centers using conventional methods. Glycosylation of the resulting alcohols under conditions for bromide-ion catalysis, provided methyl (6aS)- and (6aR)-C-alkyl-hepta-O-benzyl-α-isomaltosides. Catalytic hydrogenolysis of the benzyl groups afforded the desired disaccharides. 1H NMR studies established the absolute configurations and provided evidence for conformational preferences.Key words: amyloglucosidase (AMG), exo-anomeric effect, 6-C-alkyl-α-D-glucopyranosides and isomaltosides, mechanism of enzyme catalysis.

scholarly journals Synthesis and Characterizations of Dipeptide Derivative of Gentamicin

2019 ◽  
Vol 28 (2) ◽  
pp. 73-82
Author(s):  
Oun D. Khudair ◽  
Diar A. Fatih
Keyword(s):  
Acid Chloride ◽  
Solution Method ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Ester Linkage ◽  
Amine Groups ◽  
Conventional Solution ◽  
Dipeptide Derivative

Abstract       The target derivative are gentamicin linked with L-Val- L-Ala by an ester linkage. These were synthesized by esterification method, which included the reaction of -OH hydroxyl group on (carbon No.5) of gentamicin with the acid chloride of the corresponding dipeptide, The preparation of new derivative of gentamicin involved protected the primary & secondary amine groups of Gentamicin, by Ethylchloroformate (ECF) to give N-carbomethoxy Gentamicin which was used for further chemical synthesis involving the free hydroxyl groups. Then prepared dipeptide (L-Val- L-Ala) by conventional solution method in present DCC & HoBt then reacted with thionyl chloride to prepared acid chloride of dipeptides, then after, linked by ester linkage to N-protection gentamicin in present pyridine as base, finally deportation the amino group of synthesized compound by using TFAA in present anisole. The characterization of the titled compounds were performed utilizing FTIR spectroscopy, CHNS elemental analysis, and by measurements of their physical properties.  

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