The attachment of poly(ribitol phosphate) to lipoteichoic acid carrier

2-Acetamido-3,4,6-tri-O-acetyl-1-N-[N-(benzyloxycarbonyl)-L-aspart-1-oyl-(L-leucyl-L-threonyl-N²-tosyl-L-lysine p-nitrobenzyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine (21) and 2-acetamido-3,4,6-tri-O-acetyl-1-N-[N-(benzyloxycarbonyl)-L-aspart-1-oyl-(L-leucyl-L-threonyl-N²-tosyl-L-lysine p-nitrobenzyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine (22), 2-acetamido-3,4,6-tri-O-acetyl-1-N-[N-(benzyloxycarbonyl)-L-aspart-1-oyl-(glycine ethyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine, and 2-acetamido-3,4,6-tri-O-acetyl-1-N-[N-(benzyloxycarbonyl)-L-aspart-1-oyl-(phenylalanine methyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine were synthesized by condensation of 2-acetamido-3,4,6-tri-O-acetyl-1-N-[N-(benzyloxycarbonyl)-L-aspart-4-oyl]-2-deoxy-β-D-glucopyranosylamine with the appropriate protected amino acids and tri- and tetra-peptides. The amino acid sequences of 21 and 22 correspond to the protected amino acid sequences 34–37 and 34–38 of ribonuclease B that are adjacent to the carbohydrate-protein linkage.     

Synthesis of glycopeptide derivatives containing the 2-acetamido-N-(L-aspart-4-oyl)-2-deoxy-β-D-glucopyranosylamine linkage and having the amino acid sequences 32–34, 33–35,33–37, and 33–38 of bovine ribonuclease

The synthesis is described of the glycotripeptide derivatives 2-acetamido-3,4,6-tri-O-acetyl-N-[N-(benzyloxycarbonyl)-L--seryl-L-nitroarginyl-L-aspart-4-oyl]-2-deoxy-β-D-glucopyranosylamine, 2-acetamido-3,4,6-tri-O-acetyl-N-[N-(benzyloxycarbonyl)-L-seryl-L-nitroarginyl-L-aspart-1-oyl-(1-p-nitrobenzyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine, and 2-acetamido-3,4,6-tri-O-acetyl-N-[N-(benzyloxycarbonyl)-L-nitroarginyl-L-aspart-1-oyl-(L-leucine methyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine, and of the glycopentapeptide and glycohexapeptide derivatives 2-acetamido-3,4,6-tri-O-acetyl-N-[N-(benzyloxycarbonyl)-L-nitroarginyl-L-aspart-1-oyl-(L-leucyl-L-threonyl-threonyl-N^ε-tosyl-L-lysine-(p-nitrobenzyl ester)-4-oyl]-2-deoxy-β-D-glycopyranosylamine and 2-acetamido-3,4,6-tri-O-acetyl-N-[N-(benzyloxycarbonyl)-L-nitroarginyl-L-aspart-1-oyl-(L-leucyl-L-threonyl-N^ε-tosyl-L-lysyl-L-aspartic 1,4-di-p-nitrobenzyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine.     

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.     

Studies on dextranases. 3. Insolubilization of a bacterial dextranase

Ammonium hydroxide treatment of 1,6:2,3-dianhydro-4-O-benzyl-β-D-mannopyranose, followed by acetylation, gave 2-acetamido-3-O-acetyl-1,6-anhydro-4-O-benzyl-2-deoxy-β-D-glucopyranose which was catalytically reduced to give 2-acetamido-3-O-acetyl-1,6-anhydro-2-deoxy-β-D-glucopyranose (6), the starting material for the synthesis of (1→4)-linked disaccharides bearing a 2-acetamido-2-deoxy-D-glucopyranose reducing residue. Selective benzylation of 2-acetamido-1,6-anhydro-2-deoxy-β-D-glucopyranose gave a mixture of the 3,4-di-O-benzyl derivative and the two mono-O-benzyl derivatives, the 4-O-benzyl being preponderant. The latter derivative was acetylated, to give a compound identical with that just described. For the purpose of comparison, 2-acetamido-4-O-acetyl-1,6-anhydro-2-deoxy-β-D-glucopyranose has been prepared by selective acetylation of 2-acetamido-1,6-anhydro-2-deoxy-β-D-glucopyranose.Condensation between 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide and 6 gave, after acetolysis of the anhydro ring, the peracetylated derivative (17) of 2-acetamido-2-deoxy-4-O-β-D-glucopyranosyl-α-D-glucopyranose. A condensation of 6 with 3,4,6-tri-O-acetyl-2-deoxy-2-diphenoxyphosphorylamino-α-D-glucopyranosyl bromide likewise gave, after catalytic hydrogenation, acetylation, and acetolysis, the peracylated derivative (21) of di-N-acetylchitobiose.     

Synthesis of glycopeptides containing the amino acid sequence 17-23 of bovine pancreatic deoyxribonuclease

2-Acetamino-3,4,6-tri-O-acetly-1-N-[N-(benzyloxycarbonly-l-seryl)-l-aspart-1-oyl-(p-nitrobenzyl ester)-4-oyl]-2-deoxy-β-d-glucopyranosylamine,2-acetamido-3,4,6-tri,O-acetyl-1-N-[N-(benzyloxycarbonyl-l-seryl)-l-aspart-1-oyl-(l-alanine methyl ester)-4-oyl]-2-deoxy-β-d-glucopyranosylamine, and 2-acetamido-3,4,6-tri-O-acetyl-1-N-[N-benzyloxycarbonyl)-l-aspart-1-oyl-(l-alanyl-l-threonyl-l-leucyl-l-alanyl-l-serine p-nitrobenzyl ester)-4-oyl]-2-deoxy-β-d-glucopyranosylamine (7), which span the amino acid sequence 17-23 of bovine pancreatic deoxyribonuclease A and contain a 2-acetamido-2-deoxy-d-glucose residue, were synthesized. On treatment with lithium hydroxide, the blocked glycohexapeptide 7 gave 2-acetamido-1-N-[N-(benzyloxycarbonyl)-l-aspart-1-oyl-(l-alanyl-l-threonyl-l-leucyl-l-alanyl-l-serine)-4-oyl]-2 deoxy-β-d-glucopyranosylamine.     

Synthesis of 2-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-D-mannose,and its interaction with D-mannose-specific lectins

Condensation of 3,4:5,6-di-O-isopropylidene-D-mannose dimethyl acetal with 2-methyl-(3,4,6-tri-O-acetyl- 1,2-dideoxy-α-D-glucopyrano)-[2′, 1′:4,5]-2-oxazoline in the presence of a catalytic amount of p-toluenesulfonic acid afforded crystalline 2-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl)-3,4:5,6-di-O-isopropylidene-D-mannose dimethyl acetal (3) in 25% yield. Catalytic deacetylation of 3 with sodium methoxide, followed by hydrolysis with dilute sulfuric acid, gave 2-O-(2-acetamido-2-deoxy-α-D-glucopyranosyl)-D-mannose (4). Treatment of 3 with boiling 0.5% methanolic hydrogen chloride under reflux gave methyl 2-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-D-mannopyranoside (5) and methyl 2-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-α-D-mannofuranoside (6). The inhibitory activities of 4, 5, and 6 against the hemagglutinating and mitogenic activities of Lens culinaris and Pisum sativum lectins and concanavalin A were assayed. From the results of these hapten inhibition studies, subtle differences of specificity between these D-mannose-specific lectins were confirmed.     

The synthesis and properties of benzylated oxazolines derived from 2-acetamido-2-deoxy-D-glucose

2-Methyl-(2-acetamido-3,4,6-tri-O-benzyl-1,2-dideoxy-α-D-glucopyrano)-[2,1-d]-2-oxazoline,2-methyl-(2-acetamido-6-O-acetyl-3,4-di-O-benzyl-1,2-dideoxy-α-D-glucopyrano)-[2,1-d]-2-oxazoline,and 2-methyl-(2-acetamido-4-O-acetyl-3,6-di-O-benzyl-1,2-dideoxy-α-D-glucopyrano)-[2,1-d]-2-oxazoline were synthesized from the allyl 2-acetamido-3,4,6-tri-O-benzyl-2-deoxy-D-glucopyranosides, and from the 3,4-di-O-benzyl or 3,6-di-O-benzyl analogs, respectively, both the α and β anomer being used in each case. The preparation of allyl 2-acetamido-3,4,6-tri-O-benzyl- and 3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside is also described. Treatment of the tri-O-benzyl oxazoline with dibenzyl phosphate gave a pentabenzylglycosyl phosphate, from which all the benzyl groups were removed by catalytic hydrogenation, giving 2-acetamido-2-deoxy-α-D-glucopyranosyl phosphate. The corresponding β anomer was not detectable. Treatment of the 3,4-, or 3,6-, di-O-benzyl oxazoline with allyl 2-acetamido-3,4-di-O-benzyl-α-D-glucopyranoside readily gave disaccharide products from which the protecting groups were removed, to give the (1→6)-linked isomer of di-N-acetylchitobiose. Under both acidic and basic conditions, this isomer was less stable than the (1→4)-linked compound.Attempts to employ the 3,6-di-O-benzyl oxazoline for the formation of (1→4)-linked disaccharides, by treatment with either anomer of allyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-D-glucopyranoside, were not very successful, presumably owing to hindrance by the bulky benzyl groups.     

Synthèse des 2-acé-tamido-2-désoxy-6-O-α-et β-D-xylopyranosyl-α-D-glucopyranose

2-Acetamido-2- deoxy-6-O-, -xylopyranosyl-O-D-glucopyranose has been synthesized in crystalline form by condensation of 2,3,4-tri-O-acetyl-α-D-xylopyranosyl chloride (1) with benzyl 2-acetamido-3,4-di-O-acetyl-2-deoxy-β-D-glucopyranoside (2), followed by O-deacetylation and catalytic hydrogenation. Condensation of 2 with 2,3,4-tri-O-chlorosulfonyl-β-D-xylopyranosyl chloride, followed by dechlorosulfonylation and acetylation, gave benzyl 2-acetamido-3,4-di-O-acetyl-2-deoxy-6-O-(2,3,4-tri-O-acetyl-α-D-xylopyranosyl)β-D-glucopyranoside in crystalline form. O-Deacetylation, followed by catalytic hydrogenation, gave 2-acetamido-2-deoxy-6-O-α-D-xylopyranosyl-α-D-glucopyranose in crystalline form.     

Syntheses of 2-acetamido-2-deoxy-4-O-α-D-glucopyranosyl-α-d-glucopyranose (n-acetylmaltosamine) and 2-acetamido-2-deoxy-4-O-β-d-glucopyranosyl-α-d-glucopyranose

Condensation of benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside with 2,3,4,6-tetra-O-benzyl-1-O-(N-methyl)acetimidoyl-β-D-glucopyranose gave benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-4-O-(2,3,4,6-tetra-O-benzyl-α-D-glucopyranosyl)-α-D-glucopyranoside which was catalytically hydrogenolysed to crystalline 2-acetamido-2-deoxy-4-O-α-D-glucopyranosyl-α-D-glucopyranose (N-acetylmaltosamine). In an alternative route, the aforementioned imidate was condensed with 2-acetamido-3-O-acetyl-1,6-anhydro-2-deoxy-β-D-glucopyranose, and the resulting disaccharide was catalytically hydrogenolysed, acetylated, and acetolysed to give 2-acetamido-1,3,6-tri-O-acetyl-2-deoxy-4-O-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl)-α-D-glucopyranose Deacetylation gave N-acetylmaltosamine. The synthesis of 2-acetamido-2-deoxy-4-O-β-D-glucopyranosyl-α-D-glucopyranose involved condensation of benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide in the presence of mercuric bromide, followed by deacetylation and catalytic hydrogenolysis of the condensation product.     

Synthetic mucin fragments. Methyl 6-O-(2-acetamido-2-deoxy-β-D-glycopyranosyl)-β-D-galactopyranoside,methyl 3,4-di-O-(2-acetamido-2-deoxy-β-D-glycopyranosyl)-β-D-galactopyranoside,and methyl O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1 å 3)-O-β-D-galactopyranosyl-(1 å 3)-O-(2-acetamido-2-deoxy-β- D-glucopyranosyl)-(1 å 3)-β-D-galactopyranoside

Condensation of methyl 2,6-di-O-benzyl-β-d-galactopyranoside with 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano)-[2,1,-d]-2-oxazoline (1) in 1,2-dichloroethane, in the presence of p-toluenesulfonic acid, afforded a trisaccharide derivative which, on deacetylation, gave methyl 3,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-2,6-di-O-benzyl-β-d- glactopyranoside (5). Hydrogenolysis of the benzyl groups of 5 furnished the title trisaccharide (6). A similar condensation of methyl 2,3-di-O-benzyl-β-d-galactopyranoside with 1 produced a partially-protected disacchraide derivative, which, on O-deacetylation followed by hydrogenolysis, gave methyl 6-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-β-d-glactopyranoside (10). Condensation of methyl 3-O-(2-acetamido-4,6-O-benzylidene-2-deoxy-β-d-glucopyranosyl)-2,4,6-tri-O-benzyl-β-d- galactopyranoside with 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-2,4,6-tri-O-acetyl-α-d-galactopyranosyl bromide in 1:1 benzene-nitromethane in the presence of powdered mercuric cyanide gave a fully-protected tetrasaccharide derivative, which was O-deacetylated and then subjected to catalytic hydrogenation to furnish methyl O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-(1→3)-O-β-d-galactopyranosyl-(1å3)-O-(2-acetamido-2-deoxy- β-d-glucopyranosyl)-(1å3)-β-d-galactopyranoside (15). The structures of 6, 10, and 15 were established by ¹³C-n.m.r. spectroscopy.     

Synthesis of phenyl 2-acetamido-2-deoxy-3-O-α-l-fucopyranosyl-β-d-glucopyranoside and related compounds

The reaction of phenyl 2-acetamido-2-deoxy-4,6- O-(p-methoxybenzylidene)-β-d-glucopyranoside with 2,3,4-tri-O-benzyl-α-l-fucopyranosyl bromide under halide ion-catalyzed conditions proceeded readily, to give phenyl 2-acetamido-2-deoxy-4,6-O-(p-methoxybenzylidene)-3-O-(2,3,4-tri-O-benzyl-α-l-fucopyranosyl)-β-d-glucopyranoside (8). Mild treatment of 8 with acid, followed by hydrogenolysis, provided the disaccharide phenyl 2-acetamido-2-deoxy-3-O-α-l-fucopyranosyl-β-d-glucopyranoside. Starting from 6-(trifluoroacetamido)hexyl 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranoside, the synthesis of 6-(trifluoroacetamido)hexyl 2-acetamido-2-deoxy-3-O-β-l-fucopyranosyl-β-d-glucopyranoside has been accomplished by a similar reaction-sequence. On acetolysis, methyl 2-acetamido-2-deoxy-3-O-α-l-fucopyranosyl-α-d-glucopyranoside gave 2-methyl-[4,6-di-O-acetyl-1,2-dideoxy-3-O-(2,3,4-tri-O-acetyl-α-l-fucopyranosyl)-α-d-glucopyrano]-[2, 1-d]-2-oxazoline as the major product.     

Oxazoline synthesis of 1,2-trans-2-acetamido-2-deoxyglycosides. Glycosylation with 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-D-galactopyrano)-[2′,1′:4,5]-2-oxazoline

The glycosylating activity of 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-D-galactopyrano)-[2′,1′:4,5]-2-oxazoline has been tested in reaction with partially protected saccharides having free primary or secondary hydroxyl groups or with hydroxy amino acids. 3-O-(2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-galactopyranosyl)-N-benzyloxycarbonyl-L-serine benzyl ester (3), 6-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-D-galactopyranose (5), p-nitrophenyl 2-acetamido-6-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-2-deoxy-β-D-glucopyranoside (7), 6-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-D-glucose (9), and 3-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-D-glucose (11) were synthesized in high yield.     

The synthesis,and study of the β-elimination reaction,of di- and tri-peptides having a 3-O(2-acetamido-3,4,6-trio-O-acetyl-2-deoxy-β-D-glucopyranosyl)-L-serine residue

2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-α-D-glucopyra-nosyl chloride was condensed with the N-(benzyloxycarbonyl) derivatives of, respectively, L-seryl-glycine ethyl, L-seryl-L-alanine methyl, L-seryl-L-phenylalanine methyl, and L-seryl-L-aspartic dibenzyl esters to give (3-O-GlcpNAc-CbzN-L-Ser)-GlyOEt (8), (3-O-GlcpNAc-CbzN-L-Ser)-L-AlaOMe (9), (3-O-GlcpNAc-CbzN-L-Ser)-L-PheOMe (10), and (3-O-GlcpNAc-CbzN-L-Ser)-L-Asp(diOBzl) (11), respectively; O-(2-acetamido-3,4,6-tri-O-acetyl-β-D-glucopyranosy-l)-N-(benzyloxycarbonyl)-L-serine methyl ester was deblocked by treatment with hydrobromic acid in glacial acetic acid, followed by triethylamine, to give a glycoamino acid that was condensed with the N-(benzyloxycarbonyl) derivatives of the p-nitrophenyl ester of glycine, L-alanine, and L-proline, respectively, to give CbzNGly-(3-O)-Glcp NAc-L-SerOMe) (17), CbzN-L-Ala-(3-O-GlcpNAc-L-SerOMe), and CbzN-L-Pro-(3-O-GlcpNAc-L-SerOMe), respectively. Similarly, the glycopeptide resulting from 8 was condensed with the activated esters of glycine, L-alanine, L-phenylalanine, L-proline, and L-serine, respectively, to give CbzNGly-(3-OGlcpNAc-L-Ser)-GlyOEt, CbzN-L-Ala-(3-O-GlcpNAc-L-Ser)-GlyOEt, CbzN-L-Phe-(3-O-GlcpNAc-L-Ser)-GlyOEt, and CbzN-L-Ser-(3-O-GlcpNAc-L-Ser)-GlyOEt, respectively; that from 9, with the p-nitrophenyl esters of glycine¹,L-alanine, L-phenylalanine, L-proline, and L-leucine, respectively, to give CbzNGly-(3-O-GlcpNAc-L-Ser)-L-AlaOMe, CbzN-L-Ala(3-O-GlcpNAc-L-Ser)-L-AlaOMe, CbzN-L-Phe-(3-O-GlcpNAc-L-Ser)-L]-AlaOMe, CbzN-L-Pro-(3-O-GlcpNAc-L-Ser)-L-AlaOMe, and CbzN-L-Leu-(3-O-GlcpNAc- L-Ser)-L-AlaOMe, respectively; that from 10, with the derivatives of glycine, L-alanine, L-phenylalanine, and L-leucine, respectively, to give CbzNGly-(3-O-GlcpNAc-L-Ser)-L-PheOMe, CbzN-L-Phe-(3-O-GlcpNAc-L-Ser)-L-PheOMe, CbzN-L-Phe-(3-O-GlcpNAc-L-Ser)-L-PheOMe, and CbzN-L-Leu-(3-O-GlcpNAc-L-Ser)-L-PheOMe, respectively; and that from 11, with the derivatives of glycine, L-alanine, L-phenylalanine, L-proline, and L-leucine, respectively, to give CbzNGly-(3-O-GlcpNAc-L-Ser)-L-Asp(diOBzl), CbzN-L-Ala-(3-O-GlcpNAc-L-Ser)-L-Asp(diOBzl), CbzN-L-Phe-(3-O-GlcpNAc-L-Ser)-L-Asp(diOBzl), CbzN-L-Pro-(3-O-GlcpNAc-L-Ser)-L-Asp(diOBzl), and CbzN-L-Leu-(3-O-GlcpNAc-L-Ser)-L-Asp-(diOBzl), respectively. O-(2-Acetamido-3,4,5-tri-O-acetyl-2-deoxy-β-D-gluco-pyranosyl)-N-(benzyloxycarbonyl)- L-asparaginylglycyl-L-serine methyl ester (20) was synthesized by treating the free amine of 17 with the p-nitrophenyl ester of N-(benzyloxycarbonyl)-L-asparagine. 2-Acetamido-3,4,6-tri-O-acetyl-1-N-[N-(benzyloxycarbo-nyl)-L-aspart-1-oyl-(glycyl-L-serine methyl ester)-4-oyl]-2-deoxy-β-D-glucopyranosylamine (41) was synthesized by the condensation of 2-acetamido-3,4,6-tri-O-acetyl-1-N-[N-(benzyloxycarbo-nyl)-L-aspart-4-oyl]-2-deoxy-β-D-glucopyranosylamine with glycyl-L-serine methyl ester. Attempts to transfer the 2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-D-glucopyranosyl group from the hydroxyl group of L-serine in 20 to the amido group of L-asparagine, to give 41, were unsuccessful. The β-elimination of some of the glycodi- and glycotri-peptides was studied.     

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.     

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 methyl (or propyl) 2-acetamido-2-deoxy-α-D-glucopyranoside 6-(α-D-glucopyranosyl phosphate) and derivatives for the study of the phosphoric ester linkage in the Micrococcus lysodeikticus cell-wall

Methyl 2-acetamido-3-O-allyl-2-deoxy-4-O-methyl-α-D-glucopyranoside, methyl 2-acetamido-2-deoxy-4-O-methyl-α-D-glucopyranoside, and methyl 2-acetamido-3,4-di-O-allyl-2-deoxy-α-D-glucopyranoside, prepared from methyl 2-acetamido-2-deoxy-α-D-glucopyranoside, were coupled with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl phosphate (13), to give the phosphoric esters methyl 2-acetamido-3-O-allyl-2-deoxy-4-O-methyl-α-D-glucopyranoside 6-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl phosphate) (16), methyl 2-acetamido-2-deoxy-4-O-methyl-α-D-glucopyranoside 6-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl phosphate) (23), and methyl 2-acetamido-3,4-di-O-allyl-2-deoxy-α-D-glucopyranoside 6-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl phosphate) (17). Compound 13 was prepared from penta-O-acetyl-β-D-glucopyranose by the phosphoric acid procedure, or by acetylation of α-D-glucopyranosyl phosphate. Removal of the allyl groups from 16 and 17 gave 23 and methyl 2-acetamido-2-deoxy-α-D-glucopyranoside 6-(2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl phosphate) (19), respectively. O-Deacetylation of 23 gave methyl 2-acetamido-2-deoxy-4-O-methyl-α-D-glucopyranoside 6-(α-D-glucopyranosyl phosphate) (26) and O-deacetylation of 19 gave methyl 2-acetamido-2-deoxy-α-D-glucopyranoside 6-(α-D-glucopyranosyl phosphate) (24). Propyl 2-acetamido-2-deoxy-α-D-glucopyranoside 6-(α-D-glucopyranosyl phosphate) (25) was prepared by coupling 13 with allyl 2-acetamido-3,4-di-O-benzyl-2-deoxy-α-D-glucopyranoside, followed by catalytic hydrogenation of the product to give the propyl glycoside, which was then O-deacetylated. Compounds 24, 25, and 26 are being employed in structural studies of the Micrococcus lysodeikticus cell-wall.     

Use of 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-2,4,6-tri-O-acetyl-α-d-galactopyranosyl bromide as a glycosyl donor: Synthesis of p-nitrophenyl 3-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-β-d-galactopyranoside

Acetolysis of methyl 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-2,4,6-tri-O-acetyl-α-d-galactopyranoside afforded 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-1,2,4,6-tetra-O-acetyl-d-galactopyranose (2). Treatment of 2 in dichloromethane with hydrogen bromide in glacial acetic acid gave 3-O-(2-acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)- 2,4,6-tri-O-acetyl-α-d-galactopyranosyl bromide (3). The α configuration of 3 was indicated by its high, positive, specific rotation, and supported by its ¹H-n.m.r. spectrum. Reaction of 3 with Amberlyst A-26-p-nitrophenoxide resin in 1:4 dichloromethane-2-propanol furnished p-nitrophenyl 3-O-(2-acetamido-3,4,6- tri-O-acetyl-2-deoxy-β-d-glucopyranosyl)-2,4,6-tri-O-acetyl-β-d-galactopyranoside (7). Compound 7 was also obtained by the condensation (catalyzed by silver trifluoromethanesulfonate-2,4,6-trimethylpyridine) of 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-β-d-glucopyranosyl bromide with p-nitrophenyl 2,4,6-tri-O-acetyl-β-d-galactopyranoside, followed by the usual deacylation-peracetylation procedure. O-Deacetylation of 7 in methanolic sodium methoxide furnished the title disaccharide (8). The structure of 8 was established by ¹³C-n.m.r. spectroscopy.     

The synthesis of 5-O-(2-acetamido-2-deoxy-α-D-glucopyranosyl)-β-D-glucofuranose

Condensation of dimeric 3,4,6-tri-O-acetyl-2-deoxy-2-nitroso-α-D-glucopyranosyl chloride (1) with 1,2-O-isopropylidene-α-D-glucofuranurono-6,3-lactone (2) gave 1,2-O-isopropylidene-5-O-(3,4,6-tri-O-acetyl-2-deoxy-2-hydroxyimino-α-D-arabino-hexopyranosyl)-α-D-glucofuranurono-6,3-lactone (3). Benzoylation of the hydroxyimino group with benzoyl cyanide in acetonitrile gave 1,2-O-isopropylidene-5-O-(3,4,6-tri-O-acetyl-2-benzoyloxyimino-2-deoxy-α-D-arabino-hexopyranosyl)-α-D-glucofuranurono-6,3-lactone (4). Compound 4 was reduced with borane in tetrahydrofuran, yielding 5-O-(2-amino-2-deoxy-α-D-glucopyranosyl)-1,2-O-isopropylidene-α-D-glucofuranose (5), which was isolated as the crystalline N-acetyl derivative (6). After removal of the isopropylidene acetal, the pure, crystalline title compound (10) was obtained.     

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.     

Syntheses of 3-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-α-d-galactopyranose (“lacto-N-biose II”) and 3,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-galactopyranose

3- O-(2-Acetamido-2-deoxy-β-d-glucopyranosyl)-α-d-galactopyranose (10, “Lacto-N-biose II”) was synthesized by treatment of benzyl 6-O-allyl-2,4-di-O-benzyl-β-d-galactopyranoside with 2-methyl-(3,4,6-tri-O-acetyl-1,2-dideoxy-α-d-glucopyrano)[2,1-d]-2-oxazoline (5), followed by selective O-deallylation, O-deacetylation, and catalytic hydrogenolysis. Condensation of 5 with benzyl 6-O-allyl-2-O-benzyl-α-d-galactopyranoside, followed by removal of the protecting groups, gave 10 and a new, branched trisaccharide, 3,4-di-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-d-galactopyranose (27).