Synthesis and biological activity of O-(N-acetyl-β-muramoyl-l-alanyl-d-isoglutamine)-(1→6)-2-acylamino-2-deoxy-d-glucoses

Benzoylation of benzyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-α-d-glucopyranoside, benzyl 2-deoxy-2-(dl-3-hydroxytetradecanoylamino)-4,6-O-isopropylidene-α-d-glucopyranoside, and benzyl 2-deoxy-4,6-O-isopropylidene-2-octadecanoylamino-β-d-glucopyranoside, with subsequent hydrolysis of the 4,6-O-isopropylidene group, gave the corresponding 3-O-benzoyl derivatives (4, 5, and 7). Hydrogenation of benzyl 2-acetamido-4,6-di-O-acetyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-α-d-glucopyranoside, followed by chlorination, gave a product that was treated with mercuric actate to yield 2-acetamido-1,4,6-tri-O-acetyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-β-d-glucopyranose (11). Treatment of 11 with ferric chloride afforded the oxazoline derivative, which was condensed with 4, 5, and 7 to give the (1→6)-β-linked disaccharide derivatives 13, 15, and 17. Hydrolysis of the methyl ester group in the compounds derived from 13, 15, and 17 by 4-O-acetylation gave the corresponding free acids, which were coupled with l-alanyl-d-isoglutamine benzyl ester, to yield the dipeptide derivatives 19–21 in excellent yields. Hydrolysis of 19–21, followed by hydrogenation, gave the respective O-(N-acetyl-β-muramoyl-l-alanyl-d-isoglutamine)-(1→6)-2-acylamino-2-deoxy-d-glucoses in good yields. The immunoadjuvant activity of these compounds was examined in guinea-pigs.     

Synthesis of 2,6-di(acylamino)-2,6-dideoxy-3-O-(d-2-propanoyl-l-alanyl-d-isoglutamine)-d-glucopyranoses

Five 2,6-di(acylamino)-2,6-dideoxy-3-O-(d-2-propanoyl-l-alanyl-d-isoglutamine)-d-glucopyranoses (lipophilic, muramoyl dipeptide analogs) were synthesized from benzyl 2-(benzyloxycarbonylamino)-3-O-(d-1-carboxyethyl)-2-deoxy-5,6-O-isopropylidene-β-dglucopyranoside (1). Methanesulfonylation of 3, derived from the methyl ester of 1 by O-deisopropylidenation, gave the 6-methanesulfonate (4). (Tetrahydropyran-2-yl)ation of 4 gave benzyl 2-(benzyloxycarbonylamino)-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-6-O-(methylsulfonyl)-5-O-(tetrahydropyran-2-yl)-β-d- glucofuranoside, which was treated with sodium azide to give the corresponding 6-azido derivative (6). Condensation of benzyl 6-amino-2-(benzyloxycarbonyl-amino)-2,6-dideoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-5-O-(tetrahydropyran-2-yl)-β-d-glucofuranoside, derived from 6 by reduction, with the activated esters of octanoic, hexadecanoic, and eicosanoic acid gave the corresponding 6-N-fatty acyl derivatives (8–10). Coupling of the 2-amino derivatives, obtained from compounds 8, 9, and 10 by catalytic reduction, with the activated esters of the fatty acids, gave the 2,6-(diacylamino)-2,6-dideoxy derivatives (11–15). Condensation of the acids, formed from 11–15 by de-esterification, with the benzyl ester of l-alanyl-d-isoglutamine, and subsequent hydrolysis, afforded benzyl 2,6-di(acylamino)-2,6-dideoxy-3-O-(d-2-propanoyl-l-alanyl-d-isoglutamine benzyl ester)-β-d-glucofuranosides. Hydrogenation of the dipeptide derivatives thus obtained gave the five lipophilic analogs of 6-amino-6-deoxymuramoyl dipeptide, respectively, in good yields.     

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.     

Glycosidation at C-4 of 2-acetamido-2-deoxy-D-glucopyranose derivatives by koenigs-knorr type condensations

The condensation of 2,3,4,6-tetra-O-benzyl-D-glucopyranosyl bromide and 2,3,4,6-tetra-O-benzyl-D-mannopyranosyl chloride with benzyl 2-acetamido-3,6-di-O-benzyl-2-deoxy-α-D-glucopyranoside (1), under Koenigs-Knorr conditions, gave the fully benzylated derivatives of benzyl 2-acetamido-2-deoxy-4-O-α-D-glucopyranosyl-α-D-glucopyranoside, benzyl 2-acetamido-2-deoxy-4-O-β-D-glucopyranosyl-α-D-glucopyranoside, and benzyl 2-acetamido-2-deoxy-4-O-α-D-mannopyranosyl-α-D-glucopyranoside. Three further compounds, namely, benzyl 2-acetamido-3-O-benzyl-2-deoxy-6-O-(2,3,4,6-tetra-O-benzyl-D-glucopyranosyl)-α-D-glucopyranoside, benzyl 2-acetamido-3-O-benzyl-2-deoxy-6-O-(2,3,4,6-tetra-O-benzyl-D)-mannopyranosyl)-α-D-glucopyranoside, and benzyl 2-acetamido-3-O-benzyl-2-deoxy-4,6-di-O-(2,3,4,6-tetra-O-benzyl-D-mannopyranosyl)-α-D-glucopyranoside, were formed by reaction of the respective glycosyl halide with benzyl 2-acetamido-3-O-benzyl-2-deoxy-α-D-glucopyranoside present as contaminant in 1.     

The stereochemistry of palladium- and platinum-catalyzed hydrogenations of nitro sugar epoxides

The catalytic hydrogenation of carbohydrate α-nitroepoxides with palladium and platinum was investigated with regard to regiospecificity and stereochemistry of ring opening, and the fate of the nitro group. 5,6-Anhydro-1,2-O-isopropylidene- 6-C-nitro-α-D-glucofuranose gave 6-amino-6-deoxy-1,2-O-isopropylidene-α-D-gluco-furanose under platinum catalysis. The methyl 2,3-anhydro-4,6-O-benzylidene-3-C- nitrohexopyranosides having the β-D-gulo (4), ?-D-allo (9), α-D-manno (13), and β-D-manno (18) configurations underwent facile, hydrogenolytic ring-opening in the presence of palladium, to give, regardless of the orientation of the oxirane ring, methyl 4,6-O-benzylidene-3-deoxy-3-C-nitro-D-hexopyranosides having an equatorial nitro group (5, 10, 14, and 19, respectively). In addition, 3-deoxy-3-oximino derivatives arose in various proportions, and two of these (from 9, and from 18) were isolated crystalline. It was shown that the oximes did not result from over-hydrogenation of the 3-deoxy-3-C-nitro glycosides produced, and it is suggested that they originated from intermediary nitronic acids. By catalysis with platinum, the oxirane rings in 4, 9, 13, and 18 were opened in the same regiospecific sense as with palladium, but notable differences were observed otherwise. Compound 4 gave the amino analog of 5, whereas 9 retained the nitro group and gave the 4,6-O-(cyclohexylmethylene) analog of 10. The α-D-manno epoxide 13 reacted with concomitant debenzylidenation, to yield methyl 3-amino-3-deoxy-α-D-altropyranoside hydrochloride, whereas the β-D-manno epoxide 18 gave the corresponding, debenzylidenated amino β-D-altroside together with the 4,6-O-(cyclohexylmethylene)-3-nitro- and -3-amino-β-D-mannosides. The results are compared with literature reports on the stereochemistry of hydrogenolysis of oxiranes, and mechanisms that may operate for the nitro derivatives are discussed.     

Synthesis of some glycodipeptides containing hydroxyamino acids, and their stabilities to acids and bases

The following new compounds were prepared and characterized: N-benzyl-oxycarbonyl-O-(tetra-O-acetyl-β-D-glucopyranosyl)-N-glycyl-L-serine methyl ester (1) and L-threonine methyl ester (2), N-benzyloxycarbonyl-O-(β-D-glucopyranosyl)-N-glycyl-L-serine amide (3), N-benzyloxycarbonyl-O-(β-D-glucopyranosyl)-N-glycyl-L-threonine methyl ester (4) and L-threonine amide (5), N-benzyloxycarbonyl-O-(tri-O-acetyl-2-deoxy-2-trifluoroacetamido-β-D-glucopyranosyl)-N-glycyl-L-serine methyl ester (6), and N-benzyloxycarbonyl-O-(2-deoxy-2-trifluoroacetamido-β-D-glucopyranosyl)-N-glycyl-L-serine amide (7). Although various modifications of the Koenigs-Knorr synthesis were used, the best, over-all yields of the deacetylated dipeptide derivatives were only 5–10%. Although the products are alkali-labile, deacetylation was accomplished with methanolic ammonia. Of the deacetylated products, the threonine derivatives (4 and 5) were more rapidly hydrolyzed by acids than phenyl β-D-glucopyranoside, which in turn was more rapidly cleaved than the serine derivatives (3 and 7). The stabilities of 3, 4, 5, and 7 to sodium hydroxide and sodium borohydride were similar, and essentially complete β-elimination of the glycosyl residue occurred for the amide derivatives (3, 5, and 7). For the ester derivative 4, pH 9 was optimal; above this pH, ester hydrolysis was more rapid than β-elimination, and the resulting carboxyl derivatives did not undergo β-elimination. Under optimal conditions with sodium borohydride, the β-elimination reaction was complete, but the corresponding alanine and α-aminobutyric acid residues were not formed; presumably reductions to the amino alcohols occurred. A mechanism for the β-elimination is proposed.     

Synthesis of prumycin and related compounds

Prumycin (1) and related compounds have been synthesized from benzyl 2-(benzyloxycarbonyl)amino-2-deoxy-5,6-O-isopropylidene-β-d-glucofuranoside (4). Benzoylation of 4, followed by deisopropylidenation, gave benzyl 3-O-benzoyl-2-(benzyloxycarbonyl)amino-2-deoxy-β-d-glucofuranoside (6), which was converted, via oxidative cleavage at C-5–C-6 and subsequent reduction, into the related benzyl β-d-xylofuranoside derivative (7). Benzylation of 3-O-benzoyl-2-(benzyloxycarbonyl)-amino-2-deoxy-d-xylopyranose (8), derived from 7 by hydrolysis, afforded the corresponding derivatives (9, 11) of β- and α-d-xylopyranoside, and compound 7 as a minor product. Treatment of benzyl 3-O-benzoyl-2-(benzyloxycarbonyl)amino-2-deoxy-4-O-mesyl-β-d-xylopyranoside 10, formed by mesylation of 9, with sodium azide in N,N-dimethylformamide gave benzyl 4-azido-3-O-benzoyl-2-(benzyloxy-carbonyl)amino-2,4-dideoxy-α-l-arabinopyranoside (13), which was debenzoylated to compound 14. Selective reduction of the azide group in 14, and condensation of the 4-amine with N-[N-(benzyloxycarbonyl)-d-alaninoyloxy]succinimide, gave the corresponding derivative (15) of 1. Reductive removal of the protecting groups of 15 afforded 1. Prumycin analogs were also synthesized from compound 14. Evidence in support of the structures assigned to the new derivatives is presented.     

Synthesis of 2-acetamido-2-deoxy-5-thio-d-glucopyranose

2-Acetamido-2-deoxy-5-thio-d-glucopyranose (12) has been synthesized from methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-d-glucofuranoside (1). Benzoylation of 1, followed by O-deisopropylidenation, gave methyl 2-acetamido-3-O-benzoyl-2-deoxy-β-d-glucofuranoside, which was converted, via selective benzoylation and mesylation, into methyl 2-acetamido-3,6-di-O-benzoyl-2-deoxy-5-O-mesyl-β-d-glucofuranoside (5). Treatment of 6, formed by the action of sodium methoxide in chloroform on 5, with thiourea gave methyl 2-acetamido-2,5,6-trideoxy-5,6-epithio-β-d-glucofuranoside (7), which was converted into the 5-thio compound 9 by cleavage of the epithio ring in 7 with potassium acetate. Alkaline treatment of 10, derived from 9 by hydrolysis, afforded the title compound. Evidence in support of the structures assigned to the new derivatives is presented.     

Nucleophilic displacements of methyl 2,3-O-isopropylidene-4-O-toluene-p-sulphonyl-α-d-lyxo- and -β-l-ribo-pyranosides,and deamination of the corresponding 4-amino sugars

Reinvestigation of the reaction of methyl 2,3-O-isopropylidene-4-O-toluene-p-sulphonyl-α-d-lyxopyranoside (4) with azide ion has shown that methyl 4-deoxy-2,3-O-isopropylidene-β-l-erythro-pent-4-enopyranoside (8, ～51.5%) is formed, as well as the azido sugar 7 (～48.5%) of an S_N2 displacement. The unsaturated sugar 8 was more conveniently prepared by heating the sulphonate 4 with 1,5-diazabicyclo-[5.4.0]undec-5-ene. An azide displacement on methyl 2,3-O-isopropylidene-4-O-toluene-p-sulphonyl-β-l-ribopyranoside (12) furnished methyl 4-azido-4-deoxy-2,3-O-isopropylidene-α-d-lyxopyranoside (13, ～66%) and the unsaturated sugar 14 (～28.5%), which was also prepared by heating the sulphonate with 1,5-diazabicyclo[5.4.0]undec-5-ene. Deamination of methyl 4-amino-4-deoxy-2,3-O-isopropylidene-α-d-lyxopyranoside (5), prepared by reduction of 13, with sodium nitrite in 90% acetic acid at ～0°, yielded methyl 2,3-O-isopropylidene-α-d-lyxopyranoside (10a, 26.2%), methyl 2,3-O-isopropylidene-β-l-ribofuranoside (21a, 18.4%), and the corresponding acetates 10b (34.5%) and 21b (21.3%). These products are considered to arise by solvolysis of the bicyclic oxonium ion 29, formed as a consequence of participation by the ring-oxygen atom in the deamination reaction. Similar deamination of methyl 4-amino-4-deoxy-2,3-O-isopropylidene-β-l-ribopyranoside (6) afforded, exclusively, the products 10a (34.4%) and 10b (65.6%) of inverted configuration. Deamination of methyl 5-amino-5-deoxy-2,3-O-isopropylidene-β-d-ribofuranoside (20) gave 22ab, but no other products. An alternative synthesis of the amino sugars 5 and 6 is available by conversion of 10a into methyl 2,3-O-isopropylidene-β-l-erythro-pentopyranosid-4-ulose (11), followed by reduction of the derived oxime 15 with lithium aluminium hydride.     

The behavior of some aldoses with 2,2-dimethoxypropane-N,N-dimethylformamide-p-toluenesulfonic acid. II. At 80 degrees

Four aldohexoses were individually subjected to the reagent mixture and temperature cited in the title; in each case, the 2,2-dimethoxypropane was present in only a small molar excess and the p-toluenesulfonic acid was used in trace amounts. D-Mannose (1) afforded the known 2,3:5,6-di-O-isopropylidene-D-mannofuranose (2) in significantly higher yield than when the reaction was conducted at room temperature. The other three aldoses, however, gave products markedly different from those formed under the milder conditions. 2-Acetamido-2-deoxy-D-mannose (3) gave a mixture of products from which methyl 2-acetamido-2-deoxy-2,3-N,O-isopropylidene-5,6-O-isopropylidene-α-D-mannofuranoside (4), 2-acetamido-2-deoxy-2,3-N,O-isopropylidene-5,6-O-isopropylidene-D-mannofuranose (5a), and methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-α-D-mannofuranoside (6a) were isolated. 2-Acetamido-2-deoxy-D-galactose (11) gave compounds identified as methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-D-galactofuranoside (12a) and methyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-galactopyranoside (13a). 2-Acetamido-2-deoxy-D-glucose (16) afforded methyl 2-acetamido-2-deoxy-5,6-O-isopropylidene-β-D-glucofuranoside (17a) and methyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-glucopyranoside (18a). Evidence in support of the structures assigned to these new derivatives is presented.     

Nitrous acid deamination of methylated amino-oligosaccharide glycosides

G.l.c.-mass spectrometry has been used to characterize the products of N-deacetylation-nitrous acid deamination of per-O-methylated derivatives (8–11) of methyl 2-acetamido-2-deoxy-3-O-β-D-galactopyranosyl-α-D-glucopyranoside(1), methyl (2) and benzyl (3) 2-acetamido-2-deoxy-4-O-β-D-galactopyranosyl-β-D-glucopyranosides, and methyl 2-acetamido-2-deoxy-6-O-β-D-galactopyranosyl-α-D-glucopyranoside (4). 2,5-Anhydrohexoses have been converted into alditol trideuteriomethyl ethers, alditol acetates, and aldononitriles. The importance of side reactions that lead to the formation of 2-deoxy-2-C-formylpentofuranosides is discussed.     

Synthesis of 3-deoxy-4-O-β-D-galactopyranosyl-D-erythro-hexos-2-ulose and of some of its derivatives from lactose

3-Deoxy-4-O-β-D-galactopyranosyl-D-erythro-hexos-2-ulose (1) was obtained from lactose by reaction with benzoylhydrazine in the presence of a slightly acidic solution of p-toluidine, followed by hydrazinolysis of the product, 3-deoxy-4-O-β-D-galactopyranosyl-D-erythro-hexos-2-ulose bis(benzoylhydrazone) (3), with benzaldehyde. A variety of derivatives of 1 and 3 was prepared. Lactose aroylhydrazones were also prepared. Quantitative determination of the oxidant during the periodate oxidation of 3 was studied. Periodate oxidation of monosaccharide arylhydrazones gave glyoxal mono(arylhydrazones) which afforded the corresponding, mixed bis(hydrazones).     

The synthesis of chlorodeoxyhexofuranoid derivatives

The reaction of 1,2-O-isopropylidene-α- d-glucofuranose with sulfuryl chloride at 0° and at 50° afforded 6-chloro-6-deoxy-1,2-O-isopropylidene-α- d-glucofuranose 3,5-bis(chlorosulfate) ( 3) and 5,6-dichloro-5,6-dideoxy-1,2-O-isopropylidene-β- l-idofuranose 3-chlorosulfate ( 7, not characterised), respectively. Dechlorosulfation of 3 afforded the hydroxy derivative, whereas treatment of 3 with pyridine gave the 3,5-(cyclic sulfate). Dechlorosulfation of 7 afforded 5,6-dichloro-5,6-dideoxy-1,2-O-isopropylidene-β- l-idofuranose which, on acid hydrolysis, was converted into 3,6-anhydro-5-chloro-5-deoxy- l-idofuranose. 5-Chloro-5-deoxy-α- l-idofuranosidurono-6,3-lactone and 5-chloro-5-deoxy-β- l-idofuranurono-6,3-lactone derivatives were also prepared.     

Synthesis of 1-deoxy-3-C-methyl-d-fructose and 1-deoxy-3-C-methyl-d-sorbose

Hydroxylation of trans-1,3,4-trideoxy-5,6-O-isopropylidene-3-C-methyl-d-glycero-hex-3-enulose with osmium tetraoxide gave a mixture of 1-deoxy-5,6-O-isopropylidene-3-C-methyl-d-arabino- and -d-xylo-hexulose that was partially resolved by acetonation to give 1-deoxy-2,3:4,5-di-O-isopropylidene-3-C-methyl-β-d-fructopyranose (4), 1-deoxy-3,4:5,6-di-O-isopropylidene-3-C-methyl-keto-d-fructose (5), and 1-deoxy-2,3:4,6-di-O-isopropylidene-3-C-methyl-α-d-sorbofuranose (6). Treatment of a mixture of 4 and 5 with sodium borohydride gave, after column chromatography, 4 and 1-deoxy-3,4:5,6-di-O-isopropylidene-3-C-methyl-d-manno- and -d-gluco-hexitol. Deuterated derivatives corresponding to 4–6 were obtained when isopropylidenation was carried out with acetone-d₆. Deacetonation of 4 and 5 yielded 1-deoxy-3-C-methyl-d-fructose, and 6 similarly afforded 1-deoxy-3-C-methyl-d-sorbose.     

Stereoselectivity of glycosylation with derivatives of 2-azido-2-deoxy-d-galactopyranose. The synthesis of a determinant oligosaccharide related to blood-group a (type 1)

The stereoselective glycosylation of a model alcohol (cyclohexanol) by derivatives of 2-azido-2-deoxy-d-galactopyranose was studied under various conditions. 2-Azido-3,4,6-tri-O-benzyl-2-deoxy-β-d-galactopyranosyl chloride (9) was found to be the most efficient glycosylating agent for the synthesis of oligosaccharides containing 2-acetamido-2-deoxy-α-d-galactopyranose residues, and gave a tetrasaccharide, which is a determinant of the blood-group A (Type 1), i.e., O-α-l-fucopyranosyl-(1→2)-[O-2-acetamido-2-deoxy-α-d- galactopyranosyl-(1→3)]-O-β-d-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-d-glucose, and its trisaccharide fragment, O-2-acetamido-2-deoxy-α-d-galactopyranosyl-(1→3)-O-β-d-galactopyranosyl-(1→3)-2-acetamido-2-deoxy-d-glucose. In the course of this synthesis, the determinant trisaccharide related to the H blood-group, i.e., O-α-l-fucopyranosyl-(1→2)-O-β-d-galactopyranosyl-(1→3)-2-acetamido-2- deoxy-d-glucose, was also obtained.     

5-thio-l-rhamnose

Two routes for the synthesis of methyl 5-S-acetyl-6-deoxy-2,3-O-isopropylidene-5-thio-l-mannofuranoside (8) have been examined. Reaction of l-rhamnose with methanol in the presence of the cation-exchange resin gives methyl 6-deoxy-α-l-mannofuranoside (2), which on conventional acetonation yields methyl 6-deoxy-2,3-O- isopropylidene-α-l-mannofuranosides (3). Compounds 3 is also obtained by acetonation of l-rhamnose followed by treatment with a mixture of methanol, acetonation, Amberlite IR-120(H⁺) resin. Chlorination of 3 with triphenylphosphine-carbon tetrachloride gives methyl 5-chloro-5,6-dideoxy-2,3-O-isopropylidene-β-d-gulofuranoside (7), which reacts with potassium thioacetate to give 8. Alternatively, 3 is iodized with ruthenium tetraoxide to methyl 6-deoxy-2,3-O-isopropylidene-α-l-lyxo-hexofuranosid-5-ulose (9), which reduced by sodium borohydride mainly to methyl 6-deoxy-2,3-O-isopropylidene-β-d-gulofuranoside (10). The O-tosyl derivative of 10 reacts with potassium thioacetate to produced 8. Hydrolysis of 8 with 90% aqueous triflouroacetic acid, followed by acetolysis with a solution of acetic acid, acetic anhydride, and sulfuric acids gives an anomeric mixture of 1,2,3,4,-tetra-O-acetyl-6-deoxy-5-thio-l-mannopyranoses (12), together with a small proportion of 1,2,3,-tri-O-acetyl-5-S-acetyl-6-deoxy-5-thio-β-l-mannofuranose (13). Deacetylation of 12 or 13 gives 5-thio-l-rhamnose (6), from which crystalline 1,2,3,4-tetra-O-(p-nitrobenzoyl)-5-thio-β-l-rhamnopyranose (14) is obtained.     

Synthesis and biological activity of O-(N-acetyl-β-muramoyl-l-alanyl-d-isoglutamine)-(1→6)-2-acylamino-2-deoxy-d-glucoses

Benzoylation of benzyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-α-d-glucopyranoside, benzyl 2-deoxy-2-(dl-3-hydroxytetradecanoylamino)-4,6-O-isopropylidene-α-d-glucopyranoside, and benzyl 2-deoxy-4,6-O-isopropylidene-2-octadecanoylamino-β-d-glucopyranoside, with subsequent hydrolysis of the 4,6-O-isopropylidene group, gave the corresponding 3-O-benzoyl derivatives (4, 5, and 7). Hydrogenation of benzyl 2-acetamido-4,6-di-O-acetyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-α-d-glucopyranoside, followed by chlorination, gave a product that was treated with mercuric actate to yield 2-acetamido-1,4,6-tri-O-acetyl-2-deoxy-3-O-[d-1-(methoxycarbonyl)ethyl]-β-d-glucopyranose (11). Treatment of 11 with ferric chloride afforded the oxazoline derivative, which was condensed with 4, 5, and 7 to give the (1→6)-β-linked disaccharide derivatives 13, 15, and 17. Hydrolysis of the methyl ester group in the compounds derived from 13, 15, and 17 by 4-O-acetylation gave the corresponding free acids, which were coupled with l-alanyl-d-isoglutamine benzyl ester, to yield the dipeptide derivatives 19–21 in excellent yields. Hydrolysis of 19–21, followed by hydrogenation, gave the respective O-(N-acetyl-β-muramoyl-l-alanyl-d-isoglutamine)-(1→6)-2-acylamino-2-deoxy-d-glucoses in good yields. The immunoadjuvant activity of these compounds was examined in guinea-pigs.     

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.     

Synthesis of the 6-methyl and 3,6- and 4,6-dimethyl ethers of methyl 2-acetamido-2-deoxy-α-D-mannopyranoside

The 6-mono- (6) and 4,6- (16) and 3,6-di-methyl (25) ethers of methyl 2-acetamido-2-deoxy-α-D-mannopyranoside have been synthesized from 6-O-trityl, 4,6-O-benzylidene, and 3-O-methyl derivatives, respectively, by way of O-benzoyl and of O-allyl derivatives. The yields were respectively 37 and 43% for 6, 34 and 50% for 16, and 14 and 25% for 25. These ethers are used as standard compounds for the structure elucidation, by methylation, of polymers containing 2-amino-2-deoxy-D-mannose.     

Dr. Horace S. Isbell

Addition of ethyl isocyanoacetate in strongly basic medium to the glycosuloses 1,2:5,6-di-O-isopropylidene-α-d-ribo-hexofuranos-3-ulose (1) and 1,2-O-isopropylidene-5-O-trityl-d-erythro-pentos-3-ulose (2) gave the unsaturated derivatives (E)- and (Z)-3-deoxy-3-C-ethoxycarbonyl(formylamino)methylene-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (3 and 4), and (E)-3-deoxy-3-C-ethoxycarbonyl(formylamino)methylene-1,2-O-isopropylidene-5-O-trityl-α-d-ribofuranose (5). In weakly basic medium, ethyl isocyanoacetate and 1 gave 3-C-ethoxycarbonyl(formylamino)methyl-1,2:5,6-di-O-isopropylidene-α-d-allofuranose (12) in good yield. The oxidation of 3 and 4 with osmium tetraoxide to 3-C-ethoxalyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (17), and its subsequent reduction to 3-C-(R)-1′,2′-dihydroxyethyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (18) and its (S) epimer (19) and to 3-C-(R)-ethoxycarbonyl(hydroxy)methyl-1,2:5,6-di-O-isopropylidene-α-d-glucofuranose (21) and its (S) epimer (22) are described. Hydride reductions of 12 yielded the corresponding 3-C-(1-formylamino-2-hydroxyethyl), 3-C-(2-hydroxy-1-methylaminoethyl), and 3-C-(R)-ethoxycarbonyl(methylamino)methyl derivatives (13, 14 and 16). Catalytic reduction of 3 and 4 yielded the 3-deoxy-3-C-(R)-ethoxycarbonyl-(formylamino)methyl derivative 6 and its 3-C-(S) epimer. Further reduction of 6 gave 3-deoxy-3-C-(R)-(1-formylamino-2-hydroxyethyl)-1,2:5,6-di-O-isopropylidene-α-d-allofuranose (23) which was deformylated with hydrazine acetate to 3-C-(R)-(1-amino-2-hydroxyethyl)-3-deoxy-1,2:5,6-di-O-isopropylidene-α-d-allofuranose (24). The configurations of the branched-chains in 16, 21, and 22 were determined by o.r.d.