摘要:

Nickel sulphate efficiently catalyses oxidative glycol cleavage, using sodium hypochlorite as the primary oxidant. Suspended nickel peroxide is assumed to be the active intermediate. 2,3-Butanediol was oxidised (conversion 95%) to acetate at pH <10 and 20°C, applying a molar ratio hypochlorite: nickel:diol of 8:0.2:1. Methyl α-D-glucopyranoside was initially oxidised to disodium (R)-2-O-[(R)-carboxylato(methoxy)methyl]erythrate. Subsequently oxidation to disodium (R)-2-O-[(R)-carboxylato(methoxy)methyl]glycerate took place. β-Cyclodextrin was preferentially oxidatively cleaved (ca. 50%) between the C(2)-C(3) carbons, although oxidation at the C(6) carbon (ca. 25%) appeared to occur as well. In contrast, maltodextrin was oxidised at the primary hydroxyl functions.

ISSN:0732-8303    

DOI:10.1080/07328309608005671

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The four derivatives of β-maltosyl-(1→4)-trehalose have been synthesized, which are monodeoxygenated at the site of one of the primary hydroxyl groups. The tetrasaccharides were constructed in [2+2] block syntheses. Thus, 6′″-deoxy-β-maltosyl-(1→4)-trehalose was prepared by selective iodination of allyl 2,3,6,2′,3′-penta-O-acetyl-β-maltoside (3) followed by catalytic hydrogenolysis and coupling with 2,3-di-O-benzyl-4,6-O-benzylidene-α-D-glucopyranosyl 2′,3′,6′-tri-O-benzyl-α-D-glucopyranoside (9), and 6″-deoxy-β-maltosyl-(1→4)-trehalose by selective iodination of allyl 4′,6′-O-isopropylidene-β-maltoside (14), coupling with9, and one-step hydrogenolysis at the tetrasaccharide level. For the synthesis of 6′-deoxy-β-maltosyl-(1→4)-trehalose, the diol 2,3-di-O-benzyl-4,6-O-benzylidene-α-D-glucopyranosyl 2′,3′-di-O-benzyl-α-D-glucopyranoside (22) was selectively iodinated and glycosylated with acetobromomaltose followed by catalytic hydrogenolysis. The 6-deoxy-β-maltosyl-(1→4)-trehalose was obtained upon selective iodination of a tetrasaccharide diol.

ISSN:0732-8303    

DOI:10.1080/07328309608005672

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Acyloxymethylation of an acylated silver salt of α-trinositol gives, after deprotection, membrane permeable 1D-myo-inositol 1,2,6-tris(ethoxycarbonyloxymethyl sodium phosphate). The acyl groups, 3-(4,5-methylenedioxy-2-nitrophenyl)propanoyl, are cleaved by hydrogenolysis.

ISSN:0732-8303    

DOI:10.1080/07328309608005673

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

D-Mannitol was used as precursor for the synthesis of acyclicC2symmetric potential HIV-1 protease inhibitors. The 1- and 6-hydroxy groups of D-mannitol were substituted by -NHBoc, -NHValZ, -SAr, -SOAr and -SO2Ar and the 2-and 5-hydroxy groups were benzylated. In some products one of the central hydroxyl groups was either inverted or deoxygenated. Despite a close structural similarity to previously published inhibitors none of the products showed significant inhibitory activity against HIV-1 protease.

ISSN:0732-8303    

DOI:10.1080/07328309608005674

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Azido-phenylselenylation of 3-O-benzyl-2-deoxy-5,6-O-isopropylidene-D-arabino-1,4-anhydrohex-1-enitol (1) afforded an α/β mixture of phenyl 2-azido-3-O-benzyl-2-deoxy-5,6-O-isopropylidene-1-seleno-D-glucofuranoside (2) together with a small amount of 3-O-benzyl-2-deoxy-5,6-O-isopropylidene-2-phenylseleno-D-glucofuranosyl azide (3). Acetolysis of the mixture afforded 2-azido-2-deoxyglucofuranosyl donor (4). Hydrolysis of the acetal group and of the selenoglycoside2followed by acetylation and removal of the anomeric acetate provide an efficient access to 5,6-di-O-acetyl-2-azido-3-O-benzyl-2-deoxy-D-glucopyranose (8), synthetic equivalent of D-glucosamine.

ISSN:0732-8303    

DOI:10.1080/07328309608005675

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

2-Amino-3,4,6-tri-O-benzyl-2-deoxy-D-glucopyranose was transformed into its bis(tetrahydropyranyl)piperazine dimer (4) by reaction with 1,1′-thionyldiimidazole or 1,1′-sulfonyldiimidazole. This dimeric form of glucosamine is the first representative of this previously unknown heterocyclic ring system.

ISSN:0732-8303    

DOI:10.1080/07328309608005676

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The preparation of the spacer-containing trimers2, 3-aminopropyl 3-O-[4-O-Me-3-O-(4-N-D,L-lactoyl-3-O-Me-β-D-Quip)-α-L-Rhap]-α-L-Rhap, derivatives of the antigenic determinant of the glycopeptidolipid fromMycobacterium aviumserotype 12, are described. Thus, iodonium ion-mediated glycosylation of the spacer-containing acceptor7with ethyl 1-thio-rhamnopyranoside donor10, followed by selective deprotection of thep-methoxybenzyl group of thus obtained19gave bis-rhamnopyranoside acceptor20. Elongation of20with ethyl 4-azido-1-thio-β-D-quinovopyranoside18and subsequent reduction of the azido function in21led to trimer22. The amino group in22was coupled with both D- and L-lactic acid to give, after removal of the protective groups, trimers2.

ISSN:0732-8303    

DOI:10.1080/07328309608005677

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

It will be demonstrated that a successful synthesis of β-L-fucopyranose-1-phosphate (2), a key intermediate in the preparation of guanosine 5′-(β-L-fucopyranose)-diphosphate (1), strongly depends on the nature of the acyl protecting groups for the non-anomeric hydroxyl functions. Thus, the perbenzoylated, instead of peracetylated, α-L-fucopyranosyl trichloroacetimidate (11) or the corresponding ethyl β-thiofucopyranoside proved to be a convenient starting compound for the preparation of2. Further, condensation ofN,N′-dicyclohexyl-4-morpholinecarboxamidinium guanosine 5′-morpholidophosphate with excess2gave the title compound without concomitant formation of bisguanosine-5′-diphosphate (16).

ISSN:0732-8303    

DOI:10.1080/07328309608005678

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Each of four ganglioside GM4and GM3analogues containing 2- or 3-branched fatty alkyl residues in place of ceramide have been synthesized. Coupling ofO-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)-2,4,6-tri-O-benzoyl-α-D-galactopyranosyl trichloroacetimidate (13) orO-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-glacto-2-nonulopyranosylonate)-(2→3)-O-(2,4-di-O-acetyl-6-O-benzoyl-β-D-galactopyranosyl)-(1→4)-3-O-acetyl-2,4-di-O-benzoyl-α-D-glucopyranosyl trichloroacetimidate (14) with 2- or 3-branched fatty-alkyl-1-ols (9-12), prepared from the corresponding branched fatty acids by methyl esterification and reduction, using BF3Ot2gave the corresponding ganglioside analogues (15, 17, 19, 21, 23, 25, 27, 29) in good yields, which were coverted, viaO-deacylation and de-esterification, into the title compounds.

ISSN:0732-8303    

DOI:10.1080/07328309608005679

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Ganglioside GM3and KDN-ganglioside GM3, containing hexanoyl, decanoyl, and hexadecanoyl groups at the ceramide moiety have been synthesized. Selective reduction of the azido group inO-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)-O-(2,4-di-O-acetyl-6-O-benzoyl-β-D-galactopyranosyl)-(1→4)-O-(3-O-acetyl-2,6-di-O-benzoyl-β-D-glucopyranosyl)-(1→1)-(2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (1) andO-(methyl 4,5,7,8,9-penta-O-acetyl-3-deoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2→3)-O-(2,4-di-O-acetyl-6-O-benzoyl-β-D-galactopyranosyl)-(1→4)-O-(3-O-acetyl-2,6-di-O-benzoyl-β-D-glucopyranosyl)-(1→1)-(2S,3R,4E)-2-azido-3-O-benzoyl-4-octadecene-1,3-diol (2), coupling with hexanoic, decanoic, and hexadecanoic acids,O-deacylation, and de-esterification gave the title gangliosides GM3(11→13) and KDN-GM3(14→16) in good yields. On the other hand,O-deacylation of1and subsequent de-esterification gave 2-azido-sphingosine containing-GM3analogue17, which was converted into lyso-GM3, in which no fatty acyl group was substituted at the sphingosine residue, by selective reduction of the azido group.

ISSN:0732-8303    

DOI:10.1080/07328309608005680

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor