Glucopyranosyl Chloride Research Articles

Differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-d-glucopyranosyl chlorides and their application in the synthesis of diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside

Four differently N-protected 3,4,6-tri-O-acetyl-2-amino-2-deoxy-d-glucopyranosyl chlorides were synthesized and used as glycosyl donors in reactions with diosgenin. The following amine group protections were tested: trifluoroacetyl (TFA), 2,2,2-trichloroethoxycarbonyl (Troc), phthaloyl (Phth), and tetrachlorophthaloyl (TCP). Products of glycosylation were deprotected to yield diosgenyl 2-amino-2-deoxy-β-d-glucopyranoside. The efficiency of the procedures is discussed. Additionally, a single-crystal X-ray diffraction analysis for 3,4,6-tri-O-acetyl-2-deoxy-2-tetrachlorophthalimido-β-d-glucopyranosyl chloride is reported. Orientations of the pyranose substituents as well as the planarity of the acetoxy and phthalimide groups in the crystal lattice are discussed. Structural evidence is presented for a mesomeric effect in both groups. The preference of the cis over trans orientation of the acetoxy group is confirmed in the crystal lattice.

Synthesis and reactions of an (α- d-glucopyranosyl)phenylacetylene

Silver tetrafluoroborate promoted addition of (phenylethynyl)tributylstannane to 6-O- acetyl-2,3,4-tri-O- benzyl-α- d- glucopyranosyl chloride stereoselectively gave a crystalline (α- d-glucopyranosyl)phenylacetylene (4) in 73% yield. Compound 4 was epimerized to the β isomer through its hexacarbonyldicobalt complex, and was also converted into a C- α-glycosyl aldehyde (8) by sequential zinc reduction and ozonolysis. The sensitive aldehyde 8 was conveniently isolated and manipulated through its 1,3-diphenylimidazolidine derivative.

ChemInform Abstract: Synthesis of C‐Glycosides of N‐Acetylglucosamine by Direct Alkylation of 2‐Amino‐2‐deoxy‐2,3,4,6‐tetra‐O‐acetyl Glucopyranosyl Chloride.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and two-dimensional nuclear magnetic resonance analysis of a tetra- and a hexa-saccharide fragment of the O-specific polysaccharide of Shigella dysenteriae type 1

The synthesis of the tetra- and hexa-saccharide methyl glycosides α- d-Gal p-(1 → 3)α- d-Glc pNAc-(1 → 3)-α- l-Rha p-(1 → 3)-α- l-Rha p-OMe ( 1), and α- l-Rha p-(1 → 3)-α- l-Rha p-(1 → 2)-α- d-Gal p-(1 → 3)-α- d-Glc pNAc-(1 → 3)-α- l-Rha p-(1 → 3)α- l-Rha p-OMe ( 3) is described, which represent various epitopes of the O-specific polysaccharide of Shigella dysenteriae type 1. The following monosaccharide intermediates were used: 1,3-di- O-acetyl-2- O-benzoyl-4- O-benzyl-α- l-rhamnopyranose ( 6α), methyl 2,4-di- O-benzyl-α- l-rhamnopyranoside ( 7), methyl 2,4-di- O-benzoyl-1-thio-α- l-rhamnopyranoside ( 8), 2,3,4-tri- O-benzoyl-α- l-rhamnopyranosyl bromide ( 9), methyl 3,4,6-tri- O-benzyl-2- O-(4-methoxybenzyl)-1-thio-β- d-galactopyranoside ( 13), methyl 2,3,4,6-tetra- O-benzyl-1-thio-β- d-galactopyranoside ( 16), and 2-azido-4,6- O-benzylidene-3- O-bromoacetyl-2-deoxy-β- d-glucopyranosyl chloride ( 19). A detailed analysis of the 1H and 13C NMR spectra of oligosaccharides 1 and 3 confirmed that the hexasaccharide 3 better approaches the conformation of the native polysaccharide, than either 1 or the homologous pentasaccharide 41.

Synthesis of C-glycosides of N-acetylglucosamine by direct alkylation of 2-amino-2-deoxy-2,3,4,6-tetra-O-acetyl glucopyranosyl chloride

The β-isomer of C-glycoside, ethyl 2-acetamino-2-deoxy-3,4,6-tri-O-acetyl-β-D-glucopyranosylacetate( 3 ) was prepared stereoselectively in two steps by reaction of 2-acetamino-2-deoxy-3,4,6-tri-O-acetyl-α-D-glucopyranosyl chloride( 4 ) with potassium diethylmalonate and 18-crown-6, followed by decarboxylation.

An Efficient One-Pot Glycosylation from the Anomeric Hydroxy Glucopyranose

Abstract Reaction of 2,3,4,6-tetra-O-benzylglucopyranose with tris (dimethylamino)phosphine and carbon tetrachloride in dichloromethane has generated glucopyranosyl chloride via tris(dimethylamino)alkoxyphosphonium chloride, which effectively reacts in situ with hydroxyl compounds to form glucosides in the presence of silver triflate or trimethylsilyl triflate.

ChemInform Abstract: Free Radical‐Mediated Addition of Peracetylated 1‐Bromo‐β‐D‐ glucopyranosyl Chloride to Acrylonitrile.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis and conformational analysis of substituted 2,6-dioxabicyclo[3.1.1]heptanes: 1,3-anhydro-2,4-di- O-benzyl-6-deoxy-β- d-glucopyranose by 1H-NMR spectroscopy and molecular mechanics calculation

A highly selective ring opening reduction of methyl 3- O-allyl-2- O-benzyl-4,6- O-benzylidene-α- d-glucopyranoside provided the 2,4-di- O-benzyl derivative. This was toluenesulfonylated or iodinated and subsequently reduced to give crystalline methyl 3- O-allyl-2,4-di- O-benzyl-6-deoxy-α- d-glucopyranoside in good yield. Acid hydrolysis followed by deallylation and acetylation afforded a 1,3-diacetate which, on treatment with hydrogen chloride in diethyl ether, gave the crystalline key intermediate 3- O-acetyl-2,4-di- O-benzyl-α- d- glucopyranosyl chloride, Ring closure of the chloride with lithium methoxide afforded 1,3-anhydro-2,4-di- O-benzyl-6-deoxy-β- d-glucopyranose ( 15). Vicinal and long-range proton-proton coupling constants suggested that the conformation of the 1,3-anhydro sugar ether is essentially B 2,5 for the pyranose ring and a chair for the 1,3-dioxane ring. Molecular mechanics calculations using program MMP2 were applied to compound 15 and its analogue, 1,3-anhydro-2,4-di- O-benzyl-β- d-rhamnopyranose, and the results were in good agreement with those calculated by a modified Karplus equation and those measured on molecular models.

Tetra‐O‐acetyl‐β‐D‐glucopyranosyl chloride: Occurrence of gg and gt rotamers in the crystal and correlation between conformation at C‐6 and anomeric stabilization

AbstractAn X‐ray structural analysis of 2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosyl chloride (5β) shows the crystal lattice to contain consecutive layers of two forms, each in the 4C1 conformation, but differing in the orientation of the 6‐acetoxy group relative to the pyranoid ring: the gauche‐gauche (gg) rotamer, exhibiting standard bond lengths and torsional angles, and the gauche‐trans (gt) form, in which an unusually long C‐5—O‐5 bond distance of 1.536 Å is observed, though without major distortion of the chair conformation. In solution, only the gg form prevails. The similarity of conformational features of 5β in its gg form and of its β‐methoxy analog 7β is so close that the anomeric effects for equatorial Cl and OCH3 on a pyranoid ring must be grossly identical. — Force‐field calculations on the anomeric 1‐chloro‐ and 1‐methoxy derivatives of tetra‐acetyl‐D‐glucopyranose allow a realistic estimation of the magnitude of the anomeric effect and a surprisingly accurate assessment of the degree of anomeric stabilization in the individual C‐6 rotameric forms, the gg conformer invariably being the energetically most favored.

2-Trimethylsilylethyl glycosides. Treatment with electrophilic reagents to give trimethylsilyl- and methoxymethyl glucopyranosides and glucopyranosyl chloride

Treatment of 2-trimethylsilylethyl 2346-tetra- O-acetyl-β-D-glucopy ranoside ( -1) with trimethylsilyl trifluoromethanesulfonate trifluoromethanesulfonic acid or borontrifluoride etherate in the presence ofdimethoxymethane gave methoxymethyl 2346-tetra- O-acetyl-β-D-glucopyranoside in 54 62 and 66% yield respectively. In the absence of dimethoxymethane trimethylsilyl 2346-tetra- O-acetyl-β-D-glucopyranoside was formed in 78% yield. Treatment of I with 11-dichloromethylmethyl ether in the presence of zinc chloride gave 2346-tetra- O-acetyl-α-D-glucopyranosyl chloride in 98% yield.

ChemInform Abstract: A Convenient Synthetic Route to the Disaccharide Repeating‐Unit of Peptidoglycan.

Abstract Glycosylation of the readily accessible benzyl 2-acetamido-6-O-benzyl-2-deoxy-3-O-[(R)-1-(methoxycarbonyl)ethyl]-α- d -glucopyranoside wity 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β- d -glucopyranosyl chloride (2), using the silver triflate method in the absence of a base, afforded 65–70% of the fully protected [β- d -GlcNPhth-(1→4)-MurNAc] methyl ester derivative 4, the structure of which was ascertained on the basis of 500-MHz 1H-n.m.r. data. 2,2′-Dideoxy-2,2′-diphthalimido-β,β-trehalose hexa-acetate was a by-product. Removal of the Phth group from 4, followed by acetylation, yielded 90% of the acetylated 1,6-di-O-benzyl derivative 5, which, on saponification and catalytic hydrogenation, afforded 2-acetamido-4-O-(2-acetamido-2-deoxy-β- d -glucopyranosyl)-3-O-[(R)-1-carboxy-ethyl]-2-deoxy- d -glucopyranose. Similarly, 5 was converted into the acetylated methyl ester derivative, which, on selective removal of the methyl ester group, gave benzyl 2-acetamido-4-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β- d -glucopyranosyl)-6-O-benzyl-3-O-[(R-1-carboxyethyl]-2-deoxy-α- d -glucopyranoside. An alternative route for the preparation of 2 is described.

ChemInform Abstract: Synthesis of Kojitetraose and Kojipentaose.

Abstract Kojitriose [α- d -Glc p -(1→2)-α- d -Glc p -(1→2)- d -Glc p ], kojitetraose, and koji-pentaose have been synthesised by silver perchlorate-promoted Koenigs-Knorr type condensations, using 3,4,6-tri- O -acetyl-2- O -allyl-β- d -glucopyranosyl chloride and hepta- O -acetyl-β-kojibiosyl chloride as the key intermediates. The synthesis of α-β-Glc p -(1→2)-α- d -Glc p -(1→3)- d -Glc p is also described.

C-Glucopyranosyl derivatives from readily available 2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl chloride

Readily available 2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl chloride smoothly reacts with various silyl enol ethers and silver(I) trifluoromethanesulphonate (triflate) to afford D-C-glucopyranosyl derivatives of α-configuration in high yields, whereas reaction with an electron-rich aromatic nucleophile yields the corresponding β-anomer.

Chlorination of 1,5-anhydro-3-nitro-1-enitol derivative in various ethers and its mndo study

Chlorination of 3-nitro-D-glucal derivative in ethylene oxide and in hexamethylene oxide is described and compared with those in p -dioxane, tetrahydrofuran tetrahydropyran, trimethylene oxide, and diethyl ether; a fairly good correlation is observed between the yield of D -glucopyranosyl chloride ( 4) and methyl cation affinity.

Synthesis of 3,6-di- O-acetyl-2-deoxy-2-phthalimido-4- O-(2,3,4,6-tetra- O-acetyl-β- d-galactopyranosyl)-β- d-glucopyranosyl chloride

A lactosaminyl donor, 3,6-di- O-acetyl-2-deoxy-2-phthalimido-4- O-(2,3,4,6-tetra- O-acetyl-β- d-galactopyranosyl)-β- d- glucopyranosyl chloride, was synthesized in 10 steps, starting from 1,3,4,6-tetra- O-acetyl-2-deoxy-2-phthalimido-β- d-glucopyranose. Benzyl 3,6-di- O-benzyl-2-deoxy-2-phthalimido-β- d-glucopyranoside was prepared by regioselective benzylation at the primary hydroxyl group by the stannyl method, and was used as a key intermediate. ▪

Synthesis of O-β- d-galactopyranosyl-(1 → 4)- O-(2-acetamido-2-deoxy-β- d-glucopyranosyl)-(1 → 2)- d-mannose and its interaction with various lectins

2-Methyl-[3,6-di- O-acetyl-2-deoxy-4- O-(2,3,4,6-tetra- O-acetyl-β- d-galactopyranosyl)-α- d-glucopyrano]-[2,1- d]-2-oxazoline ( 4) was prepared from 2-acetamido-3,6-di- O-acetyl-2-deoxy-4- O-(2,3,4,6-tetra- O-acetyl-β- d-galactopyranosyl)-α- d- glucopyranosyl chloride. Condensation of 3,4:5,6-di- O-isopropylidene- d-mannose dimethyl acetal with 4 in the presence of a catalytic amount of p-toluenesulfonic acid afforded O-(2,3,4,6-tetra- O-acetyl-β- d-galactopyranosyl)-(1 → 4)- O-(2-acetamido-3,6-di- O-acetyl-2-deoxy-β- d-glucopyranosyl)-(1 → 2)-3,4:5,6-di- O-isopropylidene- d-mannose dimethyl acetal ( 6) in 8.6% yield. Catalytic deacetylation of 6 with sodium methoxide, followed by hydrolysis with dilute sulfuric acid, gave O-β- d-galactopyranosyl-(1 → 4)- O-(2-acetamido-2-deoxy-β- d-glucopyranosyl)-(1 → 2)- d-mannose ( 7). The inhibitory activities of 7 and related sugars against the hemagglutinating activities of various lectins were assayed, and 7 was found to be a good inhibitor against Phaseolus vulgaris hemagglutinin.

Synthesis of 3- O-(3,4-di- O-benzyl- α- D-glucopyranosyl01,2- O-isopropylidene- SN-glycerol

2- O-Allyl-3,4-di- O-benzyl-6- O- p-nitrobenzoyl- D-glucopyranosyl chloride was condensed with 1,2-di- O-(but-2-enyl)- sn-glycerol under conditions shown previously to give predominantly α-linkages. The product was converted into crystalline 3- O-(3,4-di- O-benzyl- α- D-glucopyranosyl)-1,2-O-isopylidine- sn-glycerol, a key intermediate for the synthesis of the glucosyl diglycerides which occur in Streptococci.

Studies on Aminosugars. XXXIII. Syntheses of 4-Azido-2,3,6-tri- O-benzyl-4-deoxy- and 6-Azido-2,3,4-tri-O-benzyl-6-deoxy-α-d-glucopyranosyl Chloride

Abstract The titled compounds (8 and 13) have been prepared as synthetic intermediates.