Synthesis of 5′-Fluoro-5′-deoxy-and 5′-Amino-5′-Deoxytoyocamycin and Sangivamycin and Some Related Derivatives

Abstract

A series of 5′-substituted analogs of toyocamycin were prepared by condensation of silylated 4-amino-6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine with protected 5-azido-5-deoxy- or 5-fluoro-5-deoxyribofuranose followed by debromination and deblocking. Alternatively, 5′-azido-5′-deoxytoyocamycin was prepared by azidation of toyocamycin. Conversion of the 5-nitrile function of the toyocamycin derivatives into a carboxamide or a thiocarboxamide gave the corresponding analogs of sangivamycin or thiosangivamycin while reduction of the 5′-azido-5′-deoxy nucleosides provided 5′-amino-5′-deoxy derivatives.     

Synthesis of Amide-Linked [(3′)CH2CO-NH(5′)] Nucleoside Analogues of Small Oligonucleotides

Abstract

We report syntheses of new amide-linked (di-penta)nucleoside analogues of antisense oligonucleotide components. Solution-phase coupling of 3′-(carboxymethyl)-3′-deoxy- and 5′-amino-5′-deoxynucleoside derivatives provides amide dimers. Activated [3′-(carboxymethyl)-3′-deoxy] units with a 5′-azido-5′-deoxy function provide “masked” 5′-amino-5′-deoxy residues for chain extension, and a 5′-O-DMT-protected unit provides the 5′-terminus for attachment to a phosphodiester linkage.     

The analysis of 2-acetamido-2-deoxyaldose derivatives by gas-liquid chromatography and mass spectrometry

Syntheses are reported of 4-substituted, 4-deoxy analogs of methyl β-D-galactopyranoside (the 4-amino-4-deoxy, 4-azido-4-deoxy, 4-bromo-4-deoxy, 4-chloro-4-deoxy, 4-deoxy-4-fluoro, 4-deoxy-4-iodo, and 4-thio derivatives) as potential substrates of D-galactose oxidase. These syntheses involved nucleophilic displacement of the 4-(p-bromophenylsulfonyl)oxy group of appropriate D-glucose derivatives, although the more reactive (trifluoromethylsulfonyl)oxy group was also utilized as a novel leaving-group. Formation of the bromo and iodo derivatives was accompanied by appreciable halogen exchange and a resulting overall retention of configuration, and formation of the thio compound was attended by competing reactions. Optical rotatory characteristics of the halogeno compounds, their triacetates, and tribenzoates are described, and “anomalous” behavior of the last group is noted.     

Preparation and reactions of sugar azides with alkynes: synthesis of sugar triazoles as antitubercular agents

5-azido-5-deoxy-xylo-, ribo-, and arabinofuranoses were prepared by the reaction of the respective 5-O-(methanesulfonyl) or p-toluenesulfonyl derivatives with NaN3 in DMF. The intermediate 5-azido-5-deoxy glycofuranoses on 1,3-cycloaddition with different alkynes in the presence of CuSO4 and sodium ascorbate gave the corresponding sugar triazoles in very good yields. The synthesized sugar triazoles were evaluated for their antitubercular activity against Mycobacterium tuberculosis H37Rv, where one of the compounds displayed mild antitubercular activity in vitro with MIC 12.5 microg/mL.     

Stereocontrolled Facile Synthesis and Biological Evaluation of (3′S) and (3′R)-3′-Amino (and Azido)-3′-Deoxy Pyranonucleosides

This article describes the synthesis of (3 ′S) and (3 ′R)-3 ′-amino-3 ′-deoxy pyranonucleosides and their precursors (3 ′S) and (3 ′R)-3 ′-azido-3 ′-deoxy pyranonucleosides. Azidation of 1,2:5,6-di-O-isopropylidene-3-O-toluenesulfonyl-α-D-allofuranose followed by hydrolysis and subsequent acetylation afforded 3-azido-3-deoxy-1,2,4,6-tetra-O-acetyl-D-glucopyranose, which upon coupling with the proper silylated bases, deacetylation, and catalytic hydrogenation, obtained the target 3 ′-amino-3 ′-deoxy-β-D-glucopyranonucleosides. The desired 1-(3 ′-amino-3 ′-deoxy-β-D-allopyranosyl)5-fluorouracil was readily prepared from the suitable imidazylate sugar after azidation followed by a protection/deprotection sequence and reduction of the unprotected azido precursor. No antiviral activity was observed for the novel nucleosides. Moderate cytostatic activity was recorded for the 5-fluorouracil derivatives.     

A non-hydrogen-bonding role for the 4-hydroxyl group of D-Galactose in its reaction with D-Galactose oxidase

Several 4-deoxy analogs of methyl β-D-galactopyranoside are oxidized by D-galactose oxidase. The rates associated with their various, axially attached 4-substituents follow the sequence OH>NH₂>F?>Cl> H; these differences are attributed mainly to variations in K_m. Other 4-deoxy analogs, namely, the 4-azido-4-deoxy, 4-bromo-4-deoxy-, 4-deoxy-4-iodo, and 4-thio derivatives were found to be inactive. These observations indicate that the axial 4-hydroxyl group of D-galactopyranose does not play a hydrogen-bonding role primarily, but constitutes a substituent of a size optimal for interaction with the enzyme.     

Synthesis and biological evaluation of alpha-mannosidase inhibitory activity of three deoxy derivatives of mannostatin A.

Three deoxy derivatives of alpha-mannosidase inhibitor mannostatin A have been synthesized and their inhibitors activity for Jack beans alpha-mannosidase evaluated in order to elucidate roles of each hydroxyl groups of the inhibitor The 1- and 2-deoxy derivatives have preserved inhibitory potentials although they lowered the activity one-hundred fold compared to the parent, but the 3-deoxy derivative lost activity.     

Syntheses of sugar-related trihydroxyazepanes from simple carbohydrates and their activities as reversible glycosidase inhibitors

Five diastereomeric trideoxy-1,6-iminohexitols were synthesised, and their inhibitory activities were determined against selected glycosidases. For comparison, 1,4,5-trideoxy-1,5-imino-D-lyxo-hexitol, the 4-deoxy derivative of 1-deoxymannojirimicin, was prepared by enzymatic isomerisation of 6-azido-3,6-dideoxy-D-ribo-hexose into the corresponding 2-ulose and subsequent hydrogenation accompanied by intramolecular reductive amination.     

Synthesis of protected 2-amino-2-deoxy-D-xylothionolactam derivatives and some aspects of their reactivity

The synthesis of polyfunctionalized delta-lactams as key intermediates of glycomimetics in the 2-acetamido-2-deoxy sugar series is presented. Starting from a chiral gamma-amino vinylic ester synthesized from Garner's aldehyde and after regioselective reduction, 1-azido-3-(N-tert-butyloxycarbonyl-2,2-dimethyloxazolidin-4-yl)-2-propene was obtained. Next, a cis-dihydroxylation reaction provided the protected D-xylitol and L-arabinitol azides. A simple protection-deprotection sequence, followed by an oxidation and a reductive cyclization, led to protected 2-amino-delta-lactams bearing a tert-butyloxycarbonyl group on the amine functionality. To explore the reactivity of such compounds, activation of the lactam into the corresponding thionolactam was performed. The resulting 2-amino-D-xylothionolactam derivative, a versatile intermediate, allowed access to a first generation of protected 2-amino-D-xylosamidoxime derivatives which are of interest as precursors of N-acetylhexosaminidase and N-acetylglucosaminyltransferase inhibitors. In this series of compounds, epimerization at C-2 was observed. AM(1) calculations performed on these analogs showed that they adopted a B(2,5) conformation and that the axial epimer was favored in the protected series whereas the equatorial epimer was preferred in the unprotected series.     

Reaction of magnesium dibromide etherate with 2,3-anhydroaldopyranosides

The reaction of some 2,3-anhydroaldo-hexo- and -pento-pyranoside derivatives with MgBr₂-etherate was found to afford bromodeoxy products in high yield. In the absence of any free hydroxyl group in the molecule, rigid bicyclic, and flexible monocyclic, 2,3-anhydro-α-d-aldopyranoside derivatives, mainly yielded 3-bromo-3-deoxy products through an unusual, diequatorial opening of the oxirane ring. In contrast, similar 2,3-anhydro derivatives having a free hydroxyl group in the molecule underwent the usual, diaxial opening of the oxirane ring, affording the 2-bromo-2-deoxy product. However, methyl 2,3-anhydro-4-O-methyl-β-d-ribopyranoside, despite the absence of a free hydroxyl group, underwent trans-diaxial opening of the oxirane ring.     

Hydrolytic activity of alpha-galactosidases against deoxy derivatives of p-nitrophenyl alpha-D-galactopyranoside

The four possible monodeoxy derivatives of p-nitrophenyl (PNP) alpha-D-galactopyranoside were synthesized, and hydrolytic activities of the alpha-galactosidase of green coffee bean, Mortierella vinacea and Aspergillus niger against them were elucidated. The 2- and 6-deoxy substrates were hydrolyzed by the enzymes from green coffee bean and M. vinacea, while they scarcely acted on the 3- and 4-deoxy compounds. On the other hand, A. niger alpha-galactosidase hydrolyzed only the 2-deoxy compound in these deoxy substrates, and the activity was very high. These results indicate that the presence of two hydroxyl groups (OH-3 and -4) is essential for the compounds to act as substrates for the enzymes of green coffee bean and M. vinacea, while the three hydroxyl groups (OH-3, -4, and -6) are necessary for the activity of the A. niger enzyme. The kinetic parameters (K(m) and Vmax) of the enzymes for the hydrolysis of PNP alpha-D-galactopyranoside and its deoxy derivatives were obtained from kinetic studies.     

Convenient synthesis of 3- and 6-deoxy-D-myo-inositol phosphate analogues from (+)-epi- and (-)-vibo-quercitols

Starting from (+)-epi- and (-)-vibo-quercitols readily produced by bioconversion of myo-inositol, some biologically interesting phosphate and polyphosphate analogues, including the Ins(1,4,5)P(3) derivatives of 3-deoxy- and 6-deoxy-D-myo-inositol, could be readily prepared in a conventional manner. In addition, chemical modification at C-2 of the 3-deoxy Ins(1,4,5)P(3) provided 2-epimer, and 2-deoxy and 2-deoxy-2-fluoro forms. Eight polyphosphate analogues obtained were assayed for biological activity against PDH-Pase and PDH-K, and G6Pase, but none proved positive.     

Mutagenic activity of 6-azido deoxyhexoses and azido alcohols in Salmonella typhimurium and its inhibition by a structure-similar carbon source in the medium

6-Azido-6-deoxy (AZd) derivatives of D-glucose, D-mannose, D-altrose, D-allose, L-idose, D-galactose, D-galactonic acid and D-galactitol, 3-azido-1,2-propanediol (azidoglycerol), 3,1-diazido-2-propanol (diazidoglycerol) and (at much higher doses) 2-azidoethanol were mutagenic in Salmonella typhimurium strains TA100 and TA1535. The mutagenic response was similar to that induced by sodium azide, i.e., the azido compounds failed to induce mutations in strain TA98, and mutagenesis was independent of plasmid pKM101, and independent of external activation. The specific mutagenicity (his+ rev/mmole) of AZd-glucose and AZd-galactose was decreased with increasing concentrations of D-glucose or D-galactose in the minimal agar medium and enhanced 100-fold or more when 0.2% citrate rather than 0.2% glucose served as the carbon source in the medium. Similarly, the mutagenic efficiency of azidoglycerol was inhibited by glycerol but not by D-glucose or D-galactose; however, the mutagenicity of sodium azide was not influenced by any of these carbon sources in the medium. The inhibition of the mutagenic action of azido hexoses and azido alcohols by non-azido structural analogs is assumed to reside in competition in transmembrane transport or for the metabolic pathways.     

An assessment of the ability of yeast cells to incorporate photolabile fatty acids into their membrane phospholipids in vivo

The photolabile fatty acids 12-azidooleic, 12-(4-azido-2-nitrophenoxy)oleic, 12-azidolauric and 12-(4-azido-2-nitrophenoxy)lauric are readily taken up in vivo by an unsaturated fatty acid auxotroph of Saccharomyces cerevisiae. A low level of the two lauric acid derivatives and none of the two oleic acid derivatives are incorporated into membrane phospholipids. Under certain conditions of growth in the presence of 12-(4-azido-2-nitrophenoxy)oleic acid, the nitrophenylazide group is metabolized to a product that lacks the photolabile azido group.     

Syntheses of the methyl glycosides of the repeating units of chondroitin 4- and 6-sulfate

3,4,6-Tri-O-acetyl-D-galactal was transformed into methyl 6-O-acetyl-2-azido-4-O-benzyl-2-deoxy-beta-D-galactopyranoside and its 4-O-acetyl-6-O-benzyl analogue, each of which was glycosylated with activated, O-acetylated derivatives of methyl D-glucopyranosyluronate. The resulting beta-(1----3)-linked disaccharide derivatives were each reductively N-acetylated, hydrogenolysed, O-sulfated, and saponified to afford the disodium salts of methyl 2-acetamido-2-deoxy-3-O-(beta-D-glucopyranosyluronic acid)-4-O-sulfo-beta-D-galactopyranoside and the 6-O-sulfo analogue. D-Galactal was also transformed into activated derivatives of 2-azido-3,6-di-O-benzyl-2-deoxy-D-galactopyranose and their 3,4-di-O-benzyl analogues with various substituents at O-4 and O-6. These glycosyl donors were condensed with 6-O-protected derivatives of methyl 2,3-di-O-benzyl-beta-D-glucopyranoside to give the beta-(1----4)-linked disaccharide derivatives, which were selectively deprotected, then oxidised at C-6 of the gluco unit, reductively N-acetylated, selectively deprotected, O-sulfated at C-4 or C-6 of the galacto unit, and hydrogenolysed to give the disodium salts of methyl 4-O-(2-acetamido-2-deoxy-4-O-sulfo-beta-D-galactopyranosyl)-beta-D- glucopyranosiduronic acid and the 6-O-sulfo analogue.     

Synthesis and cytotoxic properties of anomeric 5-substituted 3'-azido-2',3'-dideoxyuridines]

Glycosylation of trimethylsilyl derivatives of 5-benzyloxymethyl- and 5-hydroxymethyluracil with 3-azido-2,3-dideoxy-5-O-benzoyl-D-ribofuranosyl chloride (prepared from ethyl 3-azido-2,3-dideoxy-5-O-benzoyl-D-ribofuranoside) and subsequent deacylation gave in both cases a mixture of anomeric 3'-azido-2',3'-dideoxy-5-benzyloxymethyl-or 5-hydroxymethyluridines. The anomers were separated by preparative TLC and their structures were studied by UV, IR and 1H-NMR spectroscopy. It is shown that 1-(3-azido-2,3-dideoxy-alpha-D-ribofuranosyl)-5-benzyloxymethyluracil has cytotoxic activity in vitro: in 10(-5)-10(-4) M concentrations it inhibits the thymidine incorporation into DNA of CaOv cells on 78.6-95.2%.     

The use of tri-O-acetyl-D-glucal and -D-galactal in the synthesis of 3-acetamido-2,3-dideoxyhexopyranoses and -hexopyranosides

Addition of hydrazoic acid to alpha,beta-unsaturated aldehydes derived from tri-O-acetyl-D-glucal and -D-galactal gave 3-azido-2,3-dideoxyhexopyranoses. These were converted into 1,4,6-tri-O-acetyl-3-azido-2,3-dideoxyhexopyranoses as well as methyl and ethyl glycosides. Hydrogenation of the proamine group in 3-azido-2,3-dideoxy derivatives provided different 3-amino and 3-acetamido sugars. The configuration and conformation of all products were established on the basis of the 1H and 13 C NMR, IR and polarimetric data.     

Regioselective enzymatic acylation of N-acetylhexosamines

A careful choice of the reaction conditions (solvent, enzyme, acylating agent) allowed an efficient regioselective acylation of N-acetylhexosamines. 6-O-Acyl derivatives of 2-acetamido-2-deoxy- -glucopyranose (GlcNAc), 2-acetamido-2-deoxy- -galactopyranose (GalNAc) and 2-acetamido-2-deoxy- -mannopyranose (ManNAc) have been isolated from regioselective esterifications catalysed by the protease subtilisin in CH₃CN–DMSO 8:2 in good yields.     

Unexpected formation of complex bridged tetrazoles via intramolecular 1,3-dipolar cycloaddition of 1,2-O-cyanoalkylidene derivatives of 3-azido-3-deoxy-D-allose

An unexpected and interesting intramolecular side reaction occurred during the attempted synthesis of glycosyl cyanides upon treatment of 1-O-acetyl-3-azido-3-deoxyallose derivatives with TMSCN and different Lewis acids. Exo-1,2-O-cyanoalkylidene derivatives formed by neighboring group participation and attack of cyanide underwent, after Lewis-acid mediated isomerization to the endo-isomer, intramolecular azide-cyanide cycloaddition leading to the formation of tetrazoles embedded in bridged tetracyclic ring systems. The efficiency of cycloaddition is dependent on the ring structure of the sugar (pyranose or furanose). Of the studied molecules, 3-azido-1,2-O-cyanoethylidene-3-deoxy-allopyranose provides the most suitable scaffold for intramolecular [2+3] cycloaddition under exceptionally mild conditions. Our results highlight the capability of carbohydrates to act as scaffolds for the precise positioning of functional groups productive for a specific chemical reaction.