Manno Isomer Research Articles

Action of Molybdate Anion on d-Glucosone: Catalytic Conversion to Aldonates Involving C1-C2 Transposition.

Treatment of the osone (aldos-2-ulose), d-[1-13C]glucosone (1 1), with sodium molybdate at 90° for 30 h gave a mixture of d-[2-13C]gluconate (2 2) and d-[2-13C]mannonate (3 2) in an 85:15 ratio, indicating that the reaction proceeds with C1-C2 transposition similar to that observed previously with aldoses. Reactions with several singly and doubly 13C-labeled isotopomers of 1 confirmed this transposition. In contrast to the aldose reaction, the reaction with 1 is irreversible, presumably due to electrostatic repulsion between the negatively charged catalytically active bimolybdate species and the negatively charged aldonate product. The production of 2 and 3 is mediated by the formation of two structurally distinct bimolybdate complexes, one producing the gluco isomer and the other producing the manno isomer. Reaction byproducts were also observed, specifically d-[1-13C]arabinose (4 1) and [13C]formate (5), when 1 1 was used as the reactant. These byproducts appear to form from the breakdown of bimolybdate complexes via alternative pathways that compete with those responsible for aldonate formation.

Synthesis of intermediates in the formation of hydroxy piperidines and 2-azido lactones from d-erythrose

A new stereodivergent synthesis towards piperidine iminosugar and azido lactones is described. The reaction of ethylidene- d-erythrose with amide sulfur ylides gave two isomeric trans-epoxyamides which were converted to 2-azido derivatives. Hydrolysis of the allo isomer gave 2-azido-1,4-lactone while the manno isomer gave the open chain epoxyamide. The latter gave a DMJ derivative in two steps. Direct hydrolysis of ethylidene epoxyamides gave the 3,6-anhydro glyconamides.

Stereoselective Synthesis of Some 3-Nitroglucopyranosyladenine Analogues via a Nitroolefin: Intermediate as Potential Therapeutic Agents¶

Three isomers of 9-(4,6-O-benzylidene-3-deoxy-β-D-hexopyranosyl) adenines (2–4) were isolated. The manno isomer 2 could be isomerized to the gluco isomer 3. The manno (2) and galacto isomer (4) were deprotected to 5 and 7, respectively. Michael addition of some organic amines and thiolates to the nitroolefin intermediate (8) gave the corresponding 2-(substituted)-3-nitro-glucopyranosides (9a-h). Compounds 9a,c,h were deprotected to 10a,c,h. Sodium azide with 8 gave the triazolo nucleoside 11, which was deprotected to 12. 2-Deoxy-3-nitro analogue 14 was also obtained. This paper is dedicated to the memory of the late Professor Tsujiaki Hata.

Convenient synthesis of pyruvate acetals of carbohydrates by coupling of trialkylsilylated diols and pyruvates

Hexopyranoside diols, mainly 4,6-diols with α- gluco, β- gluco, α- galacto, β- galacto, and α- manno configurations could be converted effectively (40 – 74% yields), to the corresponding pyruvate acetals by the coupling of the O-trialkylsilylated, namely. O-TBDMS and/or O-TMS diols, and ethyl pyruvate in the presence of TMSOTf at temperatures between −30 °C and +3 °C. In the case of β- manno isomer, the anomerization of the β-glycoside to the α-glycoside as well as the ring contraction of the pyranoside to the furanoside predominated.

環状オリゴ糖の化学合成―シクロアワオドリンの創製

Significant attentions have been focused on the inclusion chemistry of cyclodextrins and the related compounds and synthetic studies of cyclooligosaccharides have been tarring out intensively. For example, Ogawa and coworkers reported the total synthesis of cyclodextrins and a manno isomer of cyclodextrins by means of phenylselenyl triflate promoted cycloglycosylations. Synthesis of 1-3β linked cycloglucohexaose was reported by Collins' group. Modifications of α-cyclodextrin into trimethyl, 1, 3-anhydro, and a chimera analog have also reported recently. However, cyclooligosaccharide available today is only limited to D series. As we have developed a novel thermal glycosylation procedure, which can be applied to rhamnosylation with high α-selectivity, we designed the synthesis of cyclo-L-rhamnohexaose (40), the first cyclooligosaccharide of L series. On the basis of the area where the compound has been prepared, this compound was named α-cycloawaodorin, which would open a new dimension of the inclusion chemistry.

Synthesis of methyl 2- C-acetamidomethyl-2-deoxy-α- d-glucopyranoside and its manno isomer

Synthesis of methyl 2- C-acetamidomethyl-2-deoxy-α- d-glucopyranoside and its manno isomer

An approach to the regioselective introduction of functional groups on α-(1→4) linked cyclo mannohexaose: Alkylation at O-2

Stereo- and regiocontrolled synthesis of a manno isomer of α-cyclodextrin with O-2 tetradecyl group was achieved in an unambiguous manner.

Stereoselectivity of cycloglycosylation in mannooligose series depends on carbohydrate chain length: Syntheses of manno isomers of β- and γ- cyclodextrins

Syntheses of manno isomer of β- and γ-cyclodextrins were achieved for the first time employing methylthioglycosides of α-(1→4) linked mannoheptaose and mannooctaose.

A highly stereoselective and practical synthesis of cyclomannohexaose, Cyclo{→4)-[α- d-Man p-(1→4)-] 5-α- d-Man p-(1→}, a manno isomer of cyclomaltohexaose

Phenylselenyl triflate-promoted cycloglycosylation of methyl O-(2,3,6-tri- O-benzyl-α- d-mannopyranosyl)-(1→4) - [ O-(2,3,6-tri- O-benzyl-α- d-mannopyranosyl)-(1→4)] 4-2,3,6-tri- O-benzyl-1-thio-α- d-mannopyranoside afforded 64% of cyclo{→4)-[ O-(2,3,6-tri- O-benzyl-α- d-mannopyranosyl)-(1→4)] 5- O-(2,3,6-tri- O-benzyl-α- d-mannopyranosyl)-(1→} which was then hydrogenolysed to give a manno isomer of cyclomaltohexaose (α-cyclodextrin). The key mannohexaosyl intermediate for cycloglycosylation was prepared in a stereocontrolled manner from 3,6-di- O-benzyl-4- O-chloroacetyl-2- O- p-methylbenzoyl-α- d-mannopyranosyl trichloroacetimidate and p-methoxyphenyl 3,6-di- O-benzyl-2- O- p-methylbenzoyl-α- d-mannopyranoside.

A highly efficient and stereoselective cycloglycosylation. Synthesis of cyclo???→4)-[α-Man-(1→4)]5-α-Man-(1→???, a manno isomer of α-cyclodextrin

Stereocontrolled synthesis of a manno isomer of α-cyclodextrin was achieved for the first time employing PhSeOTf promoted cycloglycosylation of octadeca-O-benzyl-α-Man-(1→4)-???α-Man-(1→4)???4-α-Man-1→SMe.

ChemInform Abstract: Photoreaction of Methyl 4,6‐O‐Benzylidene‐2,3‐dideoxy‐3‐nitro‐β‐D‐erythro‐hex‐2‐enopyranoside with 1,3‐Dioxolane and Tetrahydrofuran.

Abstract Irradiation of the title compound in 1,3-dioxolane and in tetrahydrofuran respectively afforded the d - gluco and d - manno isomers having the 1,3-dioxolan-2-yl and tetrahydrofuran-2-yl group at C-2, besides the glycosid-3-ulose and nitro alcohol; in the later case, the dimer was also isolated.

Methanolyse und Acetolyse von 2,6-Anhydroxopyranosiden

Abstract Acid catalyzed methanolysis of methyl 2,6-anhydro-α-D–altropyranoside (4) yields the dimethyl acetal 5 in accordance with the previously reported analogous reaction of the manno isomer 1, which gave 2. However, contrary to observations in the manno case it was impossible to cyclize 5 of the D-altro configuration to a furanoid glycoside. The methyl 2,6-anhydroglycosides 1 and 4 are also suitable precursors for the preparation of the acylals 7 and 8, respectively. Treatment of 1 with acetic anhydride at low temperatures allowed isolation of the mixed epimeric acetals 9a and 9b as intermediates.

Photoreaction of methyl 4,6- O-benzylidene-2,3-dideoxy-3-nitro-β- d- erythro-hex-2-enopyranoside with 1,3-dioxolane and tetrahydrofuran

Irradiation of the title compound in 1,3-dioxolane and in tetrahydrofuran respectively afforded the d- gluco and d- manno isomers having the 1,3-dioxolan-2-yl and tetrahydrofuran-2-yl group at C-2, besides the glycosid-3-ulose and nitro alcohol; in the later case, the dimer was also isolated.

Tetra- O-benzoyl-2-halohexopyranosyl halides: Preparation, assignment of configuration, and hydrolisis to enolones

Addition of bromine to 1,5-anhydro-tetra- O-benzoylhex-1-enitol 1 in tetrachloromethane yields 2-bromohexosyl bromide derivatives having the β- D- gluco (2), α- D- manno (3), and α- D- gluco configurations (4) in 6:3:1 ratios, i.e., cis-addition preponderates. Chlorination of 1 exclusively affords cis-adducts 5 and 6, their proportion varying with the solvent (∼4:1 in toluene and ∼2:1 in tetrachloromethane). Evidence for the structure and configuration of these dihalides is presented, and the stereochemistry, at C-2 in the α- D- manno dichloride 6 is proved by X-ray crystal structure analysis. The configurations of the manno isomers 3 and 6 were determined from chiroptical properties. The β- D- gluco-dibromide 2 is hydrolyzed to the tetra- O-benzoyl-α- D-hexosulose 10 on contact with silica gel, but the α- D- manno isomer 3 requires silver nitrate-acetone for conversion into the respective β-hexosulose 11, and the α- D- gluco-dibromide is hydrolyzed only with boiling silver perchlorate-acetone.

Stereoselective synthesis of the thermodynamically less stable manno isomers from a nitro sugar

Reaction of methyl 4,6- O-benzylidene-2,3-dideoxy-3-nitro-o-α-D- erythro-hex-2-enopyranoside (2) with hydrazoic acid, hydrogen cyanide, theophylline, and 2,6-dichloropurine under weakly acidic or neutral conditions resulted in the stereo-selective formation of addition products having the thermodynamically less-stable manno configuration, whereas reaction of 2 with more-basic reagents yielded mainly products having the more stable gluco configuration.

Phase transfer catalyzed reactions. I. Highly stereoselective formation of the thermodynamically less stable manno isomers from nitro sugars with active methylene compounds

Phase transfer catalyzed reactions. I. Highly stereoselective formation of the thermodynamically less stable manno isomers from nitro sugars with active methylene compounds

Equimolar oxymercuration of D-glucal triacetate with mercuric perchlorate and its application to the synthesis of 2′-deoxy disaccharides

A search for appropriate reaction conditions for the equimolar methoxymercuration of D-glucal triacetate was made by using various mercuric salts, bases, and reaction solvents. Under optimum conditions with mercuric perchlorate, sym-collidine, and acetonitrile, D-glucal triacetate underwent methoxymercuration with an equimolar amount of methanol to afford methyl 3,4,6-tri- O-acetyl-2-deoxy-2-perchloratomercuri-β- D-glucopyranoside ( 1, 26%) and its α- D- manno isomer ( 2, 49%). Equimolar oxymercuration of D-glucal triacetate with partially protected sugars, followed by subsequent demercuration of the products with sodium borohydride, afforded α- and β-linked 2′-deoxy disaccharide derivatives in moderate yields. The partially protected sugars used were 1,2,3,4-tetra- O-acetyl-β- D-glucopyranose and 1,2:3,4-di- O-isopropylidene-α- D-galactopyranose, and the corresponding products were O-(3,4,6-tri- O-acetyl-2-deoxy-α- D- arabino-hexopyranosyl)-(1→6)-1,2,3,4-tetra- O-acetyl- D-glucopyranose( 4, 23%) and its β-linked isomer ( 5, 11%) from the former, and O-(3,4,6-tri- O-acetyl-2-deoxy-α- D- arabino-hexapyranosyl)-(1→6)-1,2:3,4-di- O-isopropylidene-α- D-galactopyranose ( 9, 29%) and its β-linked isomer ( 10, 10%) from the latter. Deacetylation of these 2′-deoxy disaccharides was effected with methanolic sodium methoxide, but deacetonation was unsuccessful owing to simultaneous cleavage of the glycosidic linkage.

Cyclizations of dialdehydes with nitromethane. XIV. The isolation of four crystalline methyl 3,6-dideoxy-3-nitro-α-L-hexopyranosides

Cyclization of L′-methoxy-L-methyldiglycolic aldehyde (1) with nitromethane and sodium methoxide in methanol (40 min at room temperature) furnished four crystalline methyl 3,6-dideoxy-3-nitro-α-L-hexopyranosides in a combined yield of 75%. Chromatographic separation gave the gluco (2), manno (3), talo (4), and galacto (5) isomers in an approximate ratio of 18:8:3:1. Shortening of the reaction time to 25 min decreased the total yield to 53% at the expense of 2, the ratio of isolated products being 8:8:2.3:1.7. The configurations of the new nitro glycosides 3, 4, and 5 were proven by catalytic hydrogenation followed by N-acetylation, which gave the known 3-acetamido derivatives.

Chemistry and Metabolism of 3-Deoxy-D-mannooctulosonic Acid: I. STEREOCHEMICAL DETERMINATION

Abstract Ammonium 3-deoxy-d-glucooctulosonate and ammonium 3-deoxy-d-mannooctulosonate (KDO) have been synthesized. d-Arabinose was condensed with potassium di-t-butyl oxalacetate to give 3-deoxy-3-(t-butoxycarbonyl)-2-en-2-ol-d-mannooctulosonate γ-lactone (Compound II) and 3-deoxy-3-(t-butoxycarbonyl)-2-en-2-ol-d-glucooctulosonate γ-lactone (Compound I), which were hydrolyzed and decarboxylated to form 3-deoxy-d-glucooctulosonate γ-lactone (Compound III) and 3-deoxy-d-mannooctulosonate γ-lactone (Compound IV). Compounds III and IV were converted to V and VI. Structures were assigned on the basis of ultraviolet, infrared, and nuclear magnetic resonance spectra, optical rotation, and chemical properties. Ozonolysis of Compounds III and IV gave glucose and mannose, respectively. KDO aldolase cleaved the manno isomer (KDO), but was inactive toward the gluco isomer.

Synthesis of 1,6-anhydro-β- d-talopyranose from derivatives of d-galactose and d-mannose

Oxidation of 1,6-anhydro-3,4- O-isopropylidene-β- d-galactopyranose ( 1) with methyl sulfoxide-acetic anhydride or with ruthenium tetraoxide gave the crystalline 2-ketone ( 2) in high yield. Reduction of 2 with lithium aluminum hydride or sodium borohydride gave the d- talo isomer( 3) of 1 stereospecifically. The same reducing agents converted 1,6-anhydro-2,3- O-isopropylidene-β- d- lyxo-hexopyranos-4-ulose ( 4) stereospecifically into 1,6-anhydro-2,3- O-isopropylidene-β- d-talopyranose ( 5). Reduction of 4 with hydrogen over palladium gave a 3:1 mixture of 5 and its d- manno isomer ( 7); and, under these conditions, 2 was converted into a 1:1 mixture of 3 and 1. Mild hydrolysis of 3 or 5 gave 1,6-anhydro-β- d-talopyranose ( 6), the last 1,6-anhydro-β- d-aldohexopyranose to be described; further hydrolysis gave d-talose. N.m.r. spectral data are given for the triacetate ( 8) of 6. The ketones 2 and 4 showed optically active absorption at 330 and 300 nm, respectively, which gave rise in each case to a negative circular dichroism curve, and a Cotton effect of negative sign in the o.r.d. spectrum