Ring-opening reactions of sucrose epoxides: Synthesis of 4′-derivatives of sucrose

The 2,1′-O-isopropylidene derivative (1) of 3-O-acetyl-4,6-O-isopropylidene-α-d-glucopyranosyl 6-O-acetyl-3,4-anhydro-β-d-lyxo-hexulofuranoside and 2,3,4-tri-O-acetyl-6-O-trityl-α-d-glucopyranosyl 3,4-anhydro-1,6-di-O-trityl-β-d-lyxo-hexulofuranoside have been synthesised and 1 has been converted into 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,6-di-O-acetyl-3,4-anhydro-β-d-lyxo-hexulofuranoside (2). The S_N2 reactions of 2 with azide and chloride nucleophiles gave the corresponding 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-azido-4-deoxy-β-d-fructofuranoside (6) and 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-chloro-4-deoxy-β-d-fructofuranoside (8), respectively. The azide 6 was catalytically hydrogenated and the resulting amine was isolated as 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 4-acetamido-1,3,6-tri-O-acetyl-4-deoxy-β-d-fructofuranoside. Treatment of 5 with hydrogen bromide in glacial acetic acid followed by conventional acetylation gave 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,3,6-tri-O-acetyl-4-bromo-4-deoxy-β-d-fructofuranoside. Similar S_N2 reactions with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl 1,6-di-O-acetyl-3,4-anhydro-β-d-ribo-hexulofuranoside (12) resulted in a number of 4′-derivatives of α-d-glucopyranosyl β-d-sorbofuranoside. The regiospecific nucleophilic substitution at position 4′ in 2 and 12 has been explained on the basis of steric and polar factors.     

Synthesis of 5-O-α-and-β-d-glucopyranosyl-d-glucofuranose and 5-O-α-d-glucopyranosyl-d-fructopyranose (leucrose)

Reaction of 1,2-O-cyclopentylidene-α-d-glucofuranurono-6,3-lactone (2) with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide (1) gave 1,2-O-cyclopentylidene- 5-O-(2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl)-α-d-glucofuranurono-6,3-lactone (3, 45%) and 1,2-O-cyclopentylidene-5-O-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-α-d-glucofuranurono-6,3-lactone (4, 38%). Reduction of 3 and 4 with lithium aluminium hydride, followed by removal of the cyclopentylidene group, afforded 5-O-α-(9) and -β-d-glucopyranosyl-d-glucofuranose (12), respectively. Base-catalysed isomerization of 9 yielded crystalline 5-O-α-d-glucopyranosyl-d-fructopyranose (leucrose, 53%).     

Steroidal saponins from the leaves of Beaucarnea recurvata

Thirteen steroidal saponins were isolated from the leaves of Beaucarnea recurvata Lem. Their structures were established using one- and two-dimensional NMR spectroscopy and mass spectrometry. Six of them were identified as: 26-O-β-d-glucopyranosyl (25S)-furosta-5,20(22)-diene 1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5,20(22)-diene 1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2)-4-O-acetyl-β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25R)-furosta-5,20(22)-diene-23-one-1β,3β,26-triol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5-ene-1β,3β,22α,26-tetrol 1-O-α-l-rhamnopyranosyl-(1 → 4)-6-O-acetyl-β-d-glucopyranoside, 26-O-β-d-glucopyranosyl (25S)-furosta-5-ene-1β,3β,22α,26-tetrol 1-O-α-l-rhamnopyranosyl-(1 → 2) β-d-fucopyranoside, and 24-O-β-d-glucopyranosyl (25R)-spirost-5-ene-1β,3β,24-triol 1-O-α-l-rhamnopyranosyl-(1 → 2)-4-O-acetyl-β-d-fucopyranoside. The chemotaxonomic classification of B. recurvata in the family Ruscaceae was discussed.     

An approach to stereoselective preparation of 3-C-glycosylated d- and l-glucals

An approach to stereoselective synthesis of α- or β-3-C-glycosylated l- or d-1,2-glucals starting from the corresponding α- or β-glycopyranosylethanals is described. The key step of the approach is the stereoselective cycloaddition of chiral vinyl ethers derived from both enantiomers of mandelic acid. The preparation of 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4,6-tetra-O-benzyl-β-d-glucopyranosyl)methyl]-l-arabino-hex-1-enitol, 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4,6-tetra-O-benzyl-β-d-glucopyranosyl)methyl]-d-arabino-hex-1-enitol, and 1,5-anhydro-4,6-di-O-benzyl-2,3-dideoxy-3-C-[(2,3,4-tri-O-benzyl-α-l-fucopyranosyl)methyl]-d-arabino-hex-1-enitol serves as an example of this approach.     

Synthesis of the tetrasaccharide repeating-unit of the O-specific polysaccharide from Salmonella senftenberg

The oligosaccharide β-d-Man-(1 → 4)-α-l-Rha (1 → 3)-d-Gal-(6 ← 1)-α-d-Glc, which is the repeating unit of the O-specific polysaccharide chain of the lipopolysaccharide from Salmonella senftenberg, was obtained by glycosylation of benzyl 2,4-di-O-benzyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside or benzyl 2-O-acetyl-6-O-(2,3,4-tri-O-benzyl-6-O-p-nitrobenzoyl-α-d-glucopyranosyl)-β-d-galactopyranoside with 3-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl)-β-l-rhamnopyranose 1,2-(methyl orthoacetate) followed by removal of protecting groups.     

Chemical Syntheses of 4-O-α and -β-D-galactopyranosyl-D-galactose and 3-O-α- and -β-D-galactopyranosyl-D-galactose

Reaction of 2,3-di-O-acetyl-1,6-anhydro-β-D-galactopyranose (2) with 2,3,4,6-tetra- O-acetyl-α-D-galactopyranosyl bromide in the presence of mercuric cyanide and subsequent acetolysis gave 1,2,3,6-tetra-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl)-α-D-galactopyranose (4, 40%) and 1,2,3,6-tetra-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-α-D-galactopyranose (5, 30%). Similarly, reaction of 2,4-di-O-acetyl-1,6-anhydro-β-D-galactopyranose (3) gave 1,2,4,6-tetra-O-acetyl-3-O-(2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl)-α-D-galactopyranose (6, 46%) and 1,2,4,6-tetra-O-acetyl-3-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-α-D-galactopyranose (7, 14%). The anomeric configurations of 4-7 were assigned by n.m.r. spectroscopy. Deacetylation of 4-7 afforded 4-O-α-D-galactopyranosyl-D-galactose (8), 4-O-β-D-galactopyranosyl-D-galactose (9), 3-O-α-D-galactopyranosyl-D-galactose (10), and 3-O-β-D-galactopyranosyl-D-galactose (11), respectively.     

Synthesis of two purple-membrane glycolipids and the glycolipid sulfate O-(β-d-glucopyranosyl 3-sulfate)-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2, 3-di-O-phytanyl-sn-glycerol

The two purple-membrane glycolipids O-β-d-glucopyranosyl- and O-β-d-galactopyranosyl-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2, 3-di-O-phytanyl-sn-glycerol were prepared by coupling O-(2,3,4-tri-O-acetyl-α-d-mannopyranosyl)-(1→2)-O-(3,4,6-tri-O-acetyl-α-d-glucopyranosyl)-(1→1)-2, 3-di-O-phytanyl-sn-glycerol (9) with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide or 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide, respectively, followed by deacetylation. The glycolipid sulfate O-(β-d-glucopyranosyl 3-sulfate)-(1→6)-O-α-d-mannopyranosyl-(1→2)-O-α-d-glucopyranosyl-(1→1)-2,3-di-O-phytanyl-sn-glycerol was prepared by coupling of 9 with 2,4,6-tri-O-acetyl-3-O-trichloroethyloxycarbonyl-α-d-glucopyranosyl bromide in the presence of Hg(CN)₂/HgBr₂ followed by selective removal of the 3?-trichloroethyloxycarbonyl group, sulfation of HO-3?, and deacetylation. The suitably protected key-intermediate 9 could be prepared by two distinct approaches.     

Unusual properties of glycuronans [poly(glycosyluronic) compounds]

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.     

Thio and seleno sugar esters of dialkylarsinous acids

The syntheses of 2,3,4,6-tetra-O-acetyl-1-S-dimethylarsino-1-thio-β-D-glucopyranose (3), 2,3,4,6-tetra-O-acetyl-1-Se-dimethylarsino-1-seleno-β-D-glucopyranose (4), 1-S-dimethylarsino-1-thio-β-D-glucopyranose (5), and -1-Se-dimethylarsino-1-seleno-β-D-glucopyranose (7) are described. The n.m.r., Raman, and mass-spectral properties of the compounds are given. 3-O-Diethylarsino-1,2:5,6-di-O-isopropylidene-α-D-glucofuranose has also been prepared, but characterized only by n.m.r. spectroscopy.     

Synthesis and antimicrobial activity of some new N-glycosides of 2-thioxo-4-thiazolidinone derivatives

5-Arylidene-2-thioxo-4-thiazolidinones 3a-f react with each of 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl and α-d-galactopyranosyl bromides 4a,b in acetone in the presence of aqueous potassium hydroxide at room temperature to afford N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl) or N-(2,3,4,6-tetra-O-acetyl-β-d-galactopyranosyl) 2-thioxo-4-thiazolidinone derivatives 5a-f. Similarly, the reaction of 5-cycloalkylidene-2-thioxo-4-thiazolidinones 7a,b with 4a gave the corresponding N-glucosides 8a,b. Also, 5-pyrazolidene rhodanines 10a-e react with 4a to afford the new N-glucosides 11a-e. Treatment of compounds 15 and 16 with 4a in the presence of few drops of triethylamine or in KOH solution accomplished the mono- and bis-nucleosides 17 and 18, respectively. Some selected products were tested for their antimicrobial activities.     

Synthesis of O-β-d-mannopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→3)-d-galactopyranose,the trisaccharide repeating-unit of the O-specific polysaccharide from Salmonella anatum

Glycosylation of 1,2:5,6-di-O-isopropylidene-α-d-galactofuranose with 2,3-di-O-acetyl-4-O-(2,3,4,6-tetra-O-acetyl-β-d-mannopyranosyl)-α-l-rhamnopyranosyl bromide, followed by removal of the protecting groups, gave O-β-d-mannopyranosyl-(1→4)-O-α-l-rhamnopyranosyl-(1→3)-d-galactose, which is the trisaccharide repeating-unit of the O-specific polysaccharide chain of the lipopolysaccharide from Salmonella anatum. The formation of the β-d-mannopyranosyl linkage was achieved by a glucose-mannose conversion via stereoselective reduction of the corresponding oxo-disaccharide.     

The synthesis of oligosaccharide-asparagine compounds. V. O- -D-mannopyranosyl-(1 leads to 6)-O-(2-acetamido-2-deoxy- -D-glucopyranosyl)-(1 leads to 4)-2-acetamido-N-(L-aspart-4-oyl)-2-deoxy- -D-glucopyranosylamine

O-α-d-Mannopyranosyl-(1→6)-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→4)-2-acetamido-N-(l-aspart-4-oyl)-2-deoxy-β-d-glucopyranosylamine (12), used in the synthesis of glycopeptides and as a reference compound in the structure elucidation of glycoproteins, was synthesized via condensation of 2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl bromide with 2-acetamido-4-O-(2-acetamido-3-O-acetyl-2-deoxy-β-d-glucopyranosyl)-3,6-di-O-acetyl-2-deoxy-β-d-glucopyranosyl azide (5) to give the intermediate, trisaccharide azide 7. [Compound 5 was obtained from the known 2-acetamido-4-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-3,6-di-O-acetyl-2-deoxy-β-d-glucopyranosyl azide by de-O-acetylation, condensation with benzaldehyde, acetylation, and removal of the benzylidene group.] The trisaccharide azide 6 was then acetylated, and the acetate reduced in the presence of Adams' catalyst. The resulting amine was condensed with 1-benzyl N-(benzyloxycarbonyl)-l-aspartate, and the O-acetyl, N-(benzyloxycarbonyl), and benzyl protective groups were removed, to give the title compound.     

Synthese der “repeating unit” der O-spezifischen kette des lipopolysaccharides aus Aeromonas salmonicida

8-Methoxycarbonyloctyl 2-azido-4,6-O-benzylidene-2-deoxy-β-d-mannopyranoside reacted with 2,3,4-tri-O-acetyl-α-l-rhamnopyranosyl bromide to give a disaccharide from the which the glycosyl-acceptor 8-methoxycarbonyloctyl 2-azido-4,6-O-benzylidene-2-deoxy-3-O-(2,4,-di-O-acetyl-α-l-rhamnopyranosyl)-β-d-manno pyranoside (19) was obtained. This glycosyl-acceptor with 2,3,4,6-tetra-O-benzyl-α-d-glucopyranosyl chloride to give trisaccharide derivative 22 and with 2,3,6-tri-O-(α-²H₂)benzyl-4-O-(2,3,4,6-tetra-O-(α-²H₂)benzyl-α-d-glucopyranosyl)-α-d-glucopyranosyl chloride to give tetrasaccharide derivative 29. Deblocking of 22 yielded 8-methoxycarbonyloctyl O-(α-d-glucopyranosyl)-(1→3)-O-α-l-rhamnopyranosyl-(1→3)-2-acetamido-2-deoxy-β-d-mannopyranoside and deblocking of 29 8-methoxycarbonyloctyle O-α-d-glucopyranosyl-(1→4)-O-α-d-glucopyranosyl-(1→3)-O-α-l-rhamnopyranosyl- (1→3)-2-acetamido-2-deoxy-β-d-mannopyranoside. Both oligosaccharides represent the “repeating unit” of the O-specific chain of the lipopolysaccharide from Aeromonas salmonicida.     

The preparation of carbohydrate-protein conjugates: cyanuric trichloride coupling of 2-aminoethyl glycosides,and mixed-anhydride coupling of 8-carboxyoctyl glycosides to bovine serum albumin

Preparation of the following glycosides is described: 2-aminoethyl β-d-glycosides of (A) 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-d-glucopyranose, (B) 2-acetamido-4-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-3,6-di-O-acetyl-2-deoxy-β-d-glucopyranose (N,N′-diacetylchitobiose pentaacetate), (C) 4-O-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)-2,3,6-tri-O-acetyl-β-d-glucopyranose (cellobiose heptaacetate); 8-carboxyoctyl glycosides of (D) cellobiose, and (E) N,N′-diacetylchitobiose. Conjugates were prepared from (A), (B), and (C) by coupling to bovine serum albumin by cyanuric trichloride and subsequent deacetylation; (D) and (E) were coupled to bovine serum albumin by the mixed-anhydride reaction. Conjugates (A) and (B) were insoluble; conjugates (C), (D), and (E) functioned as artificial antigens and gave rise to precipitating antibodies in rabbits. Specificities of the antisera were determined by inhibition studies.     

Synthesis of three oligosaccharides that form part of the complex type of carbohydrate moiety of glycoproteins

Silver trifluoromethanesulfonate-promoted condensation of 3,4,6-tri-O-acetyl-2-deoxy-phthalimido-β-d-glucopyranosyl bromide with benzyl 3,6-di-O-benzyl-α-d-mannopyranoside and benzyl 3,4-di-O-benzyl-α-d-mannopyranoside gave the protected 2,4- and 2,6-linked trisaccharides in yields of 54 and 32%, respectively. After exchanging the 2-deoxy-2-phthalimido groups for 2-acetamido-2-deoxy groups and de-blocking, the trisaccharides 2,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-mannose and 2,6-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-mannose were obtained. Similar condensation 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 bromide with benzyl 3,4-di-O-benzyl-α-d-mannopyranoside gave a pentasaccharide derivative in 52% yield. After transformations analogous to those applied to the trisaccharides, 2,6-di-O-[β-d-galactopyranosyl-(1→4)-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)]-d-mannose was obtained.     

Synthesis of C-(d-glycopyranosyl)ethylamines and C-(d-glycofuranosyl)methylamines as potential glycosidase inhibitors

The C-glucosyl aldehyde, 2-C-(2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl)ethanal was prepared from the C-glucopyranosyl propene precursor by ozonolysis. Reductive amination of the C-glucosyl aldehyde and subsequent deprotection gave 1-anilino-2-C-(α-d-glucopyranosyl)ethane. The E and Z isomers of the oxime derivative, 1-C-(α-d-arabinofuranosyl)methanal oxime were prepared by treating their aldehyde precursor with hydroxylamine. Acetylation of the oxime, followed by catalytic hydrogenation and deprotection, gave the corresponding 1-C-(α-d-arabinofuranosyl)methylamine. Reductive amination of ethyl 2,3-O-isopropylidene-α-d-lyxo-pentodialdo-1,4-furanoside using aniline gave ethyl 5-anilino-5-deoxy-d-lyxo-furanoside. Inhibition studies with these compounds on β-d-glucosidase from sweet almond, using o-nitrophenyl d-glucopyranoside as substrate, were carried out.     

Chemical modification of aminocyclitol antibiotics

The aminocyclitol antibiotic neamine has been chemically modified at the hydroxyl group on C-6 of the 2-deoxystreptamine moiety. The partially acetylated neamine derivatives, 6,3′,4′-tri-O-acetyl- (3) and 5,3′,4′-tri-O-acetyl-1,3,2′,6′-tetra-N-(ethoxycarbonyl)neamine (4), were prepared by random hydrolysis of the 5,6-O-ethoxyethylidene derivative (2), followed by chromatographic purification. Condensation of 4 and 2,3,5-tri-O-benzoyl-d-ribofuranosyl chloride led to 6-O-(β-d-ribofuranosyl)neamine (7). Analogous condensation of 4 with 2,3,4,6-tetra-O-acetyl-α-d-glucopyranosyl bromide or 2,3,4,6-tetra-O-acetyl-α-d-galactopyranosyl bromide afforded the corresponding 6-O-(d-hexopyranosyl)neamines.     

Synthesis, antifungal activities, and potential detoxification of N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)thiocarbamates

A series of N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)thiocarbamates were synthesized by the reaction of glucosyl isothiocyanates with monohydric and dihydric alcohols, and acetone oxime, using methods of both normal reaction and microwave-assisted synthesis. Antifungal activities of the title compounds were determined with three kinds of plant pathogenic fungi, Fusarium graminearum, Rhizoctoria cerealis, and Colletotrichum orbiculare. The synthesized glucosyl thiocarbamates easily reacted with HgCl₂ to give novel metal-organic compounds, bis[O-alkyl N-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl)thiocarbamato]mercury, in yields of 80%. This strong affinity of thiocarbamates for mercury showed their potential utility in medical or marine environmental detoxification.     

Synthesis of 2-acetamido-2-deoxy-3-O-β-d-mannopyranosyl-d-glucose

Condensation of 4,6-di-O-acetyl-2,3-O-carbonyl-α-d-mannopyranosyl bromide with benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside (2) gave an α-d-linked disaccharide, further transformed by removal of the carbonyl and benzylidene groups and acetylation into the previously reported benzyl 2-acetamido-4,6-O-benzylidene-2-deoxy-3-O-(2,3,4,6-tetra-O-acetyl-α-d-mannopyranosyl)-α-d-glucopyranoside. Condensation of 3,4,6-tri-O-benzyl-1,2-O-(1-ethoxyethylidene)-α-d-glucopyranose or 2-O-acetyl-3,4,6-tri-O-benzyl-α-d-glucopyranosyl bromide with 2 gave benzyl 2-acetamido-3-O-(2-O-acetyl-3,4,6-tri-O-benzyl-β-d-glucopyranosyl)-4,6-O-benzylidene-2-deoxy-α-d-glucopyranoside. Removal of the acetyl group at O-2, followed by oxidation with acetic anhydride-dimethyl sulfoxide, gave the β-d-arabino-hexosid-2-ulose 14. Reduction with sodium borohydride, and removal of the protective groups, gave 2-acetamido-2-deoxy-3-O-β-d-mannopyranosyl-d-glucose, which was characterized as the heptaacetate. The anomeric configuration of the glycosidic linkage was ascertained by comparison with the α-d-linked analog.     

Observations on the possible application of glycosyl disulphides,sulphenic esters,and sulphones in the synthesis of glycosides

Partial desulphuration of tetra-O-acetyl-β-d-glucopyranosyl phenyl disulphide with a phosphine derivative gave 40% of phenyl 2,3,4,6-tetra-O-acetyl-1-thio-α-d- glucopyranoside and a similar proportion of β-d-glucopyranosyl 1-thio-α-d-glucopyranoside octa-acetate, showing that this procedure is of limited value in α-d-thio-glucoside synthesis. Similar treatment of allyl tetra-O-acetyl-,β-d-glucopyranosyl sulphoxide caused abstraction of oxygen, rather than of sulphur, from the derived allyl glucosylsulphenate. The phenylsulphonyl group was not readily displaced from β-d-glucopyranosyl phenyl sulphone, except intramolecularly, nor could it be displaced from the tetrabenzyl ether. Elimination of benzyl alcohol from this compound afforded a new 1-(phenylsulphonyl)glycal derivative.