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Cucumbers have been anecdotally claimed to have anti-inflammatory activity for a long time, but the active principle was not identified. idoBR1, (2 R ,3 R ,4 R ,5 S )-3,4,5-trihydroxypiperidine-2-carboxylic acid, is an iminosugar amino acid isolated from fruits of certain cucumbers, Cucumis sativus (Cucurbitaceae). It has no chromophore and analytically behaves like an amino acid making detection and identification difficult. It has anti-inflammatory activity reducing lipopolysaccharide (LPS)-induced tumor necrosis factor alpha (TNF-α) in THP-1 cells and ex vivo human blood. It showed selective inhibition of human α-l-iduronidase and sialidases from both bacteria ( Tannerella forsythia ) and human THP-1 cells. idoBR1 and cucumber extract reduced the binding of hyaluronic acid (HA) to CD44 in LPS-stimulated THP-1 cells and may function as an anti-inflammatory agent by inhibiting induced sialidase involved in the production of functionally active HA adhesive CD44. Similar to the related iminosugars, idoBR1 is excreted unchanged in urine following consumption. Its importance in the diet should be further evaluated., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

A practical synthesis of the very rare sugar d-idose and the stable building blocks for d-idose, d-iduronic, and d-idonic acids from ido -heptonic acid requires only isopropylidene protection, Shing silica gel-supported periodate cleavage of the C6-C7 bond of the heptonic acid, and selective reduction of C1 and/or C6. d-Idose is the most unstable of all the aldohexoses and a stable precursor which be stored and then converted under very mild conditions into d-idose is easily prepared.

DMDP acetic acid [N-carboxymethyl-2,5-dideoxy-2,5-imino-D-mannitol] 5 from Stevia rebaudiana is the first isolated natural amino acid derived from iminosugars bearing an N-alkyl acid side chain; it is clear from GCMS studies that such derivatives with acetic and propionic acids are common in a broad range of plants including mulberry, Baphia, and English bluebells, but that they are very difficult to purify. Reaction of unprotected pyrrolidine iminosugars with aqueous glyoxal gives the corresponding N-acetic acids in very high yield; Michael addition of both pyrrolidine and piperidine iminosugars and that of polyhydroxylated prolines to tert-butyl acrylate give the corresponding N-propionic acids in which the amino group of β-alanine is incorporated into the heterocyclic ring. These easy syntheses allow the identification of this new class of amino acid in plant extracts and provide pure samples for biological evaluation. DMDP N-acetic and propionic acids are potent α-galactosidase inhibitors in contrast to potent β-galactosidase inhibition by DMDP.

The affinity of a series of iminosugar-based inhibitors exhibiting various ring sizes toward Hex A and their essential interactions with the enzyme active site were investigated. All the Hex A-inhibiting iminosugars tested formed hydrogen bonds with Arg178, Asp322, Tyr421 and Glu462 and had the favorable cation-π interaction with Trp460. Among them, DMDP amide (6) proved to be the most potent competitive inhibitor with a K i value of 0.041 μM. We analyzed the dynamic properties of both DMDP amide (6) and DNJNAc (1) in aqueous solution using molecular dynamics (MD) calculations; the distance of the interaction between Asp322 and 3-OH and Glu323 and 6-OH was important for stable interactions with Hex A, reducing fluctuations in the plasticity of the active site. DMDP amide (6) dose-dependently increased intracellular Hex A activity in the G269S mutant cells and restored Hex A activity up to approximately 43% of the wild type level; this effect clearly exceeded the border line treatment for Tay-Sachs disease, which is regarded as 10-15% of the wild type level. This is a significantly greater effect than that of pyrimethamine, which is currently in Phase 2 clinical trials. DMDP amide (6), therefore, represents a new promising pharmacological chaperone candidate for the treatment of Tay-Sachs disease.

This paper explores the computer modelling aided design and synthesis of β-N-acetylhexosaminidase inhibitors along with their applicability to human disease treatment through biological evaluation in both an enzymatic and cellular setting. We investigated the importance of individual stereocenters, variations in structure-activity relationships along with factors influencing cell penetration. To achieve these goals we modified nitrogen heterocycles in terms of ring size, side chains present and ring nitrogen derivatization. By reducing the inhibitor interactions with the active site down to the essentials we were able to determine that besides the established 2S,3R trans-relationship, the presence and stereochemistry of the CH 2 OH side chain is of crucial importance for activity. In terms of cellular penetration, N-butyl side chains favour cellar uptake, while hydroxy- and carboxy-group bearing sidechains on the ring nitrogen retarded cellular penetration. Furthermore we show an early proof of principle study that β-N-acetylhexosaminidase inhibitors can be applicable to use in a potential anti-invasive anti-cancer strategy.

External control of gene expression is crucial in synthetic biology and biotechnology research and applications, and is commonly achieved using inducible promoter systems. The E. coli rhamnose-inducible rhaBAD promoter has properties superior to more commonly used inducible expression systems, but is marred by transient expression caused by degradation of the native inducer, l-rhamnose. To address this problem, 35 analogues of l-rhamnose were screened for induction of the rhaBAD promoter, but no strong inducers were identified. In the native configuration, an inducer must bind and activate two transcriptional activators, RhaR and RhaS. Therefore, the expression system was reconfigured to decouple the rhaBAD promoter from the native rhaSR regulatory cascade so that candidate inducers need only activate the terminal transcription factor RhaS. Rescreening the 35 compounds using the modified rhaBAD expression system revealed several promising inducers. These were characterized further to determine the strength, kinetics, and concentration-dependence of induction; whether the inducer was used as a carbon source by E. coli; and the modality (distribution) of induction among populations of cells. l-Mannose was found to be the most useful orthogonal inducer, providing an even greater range of induction than the native inducer l-rhamnose, and crucially, allowing sustained induction instead of transient induction. These findings address the key limitation of the rhaBAD expression system and suggest it may now be the most suitable system for many applications.

In the search for alternative non-metabolizable inducers in the l-rhamnose promoter system, the synthesis of fifteen 6-deoxyhexoses from l-rhamnose demonstrates the value of synergy between biotechnology and chemistry. The readily available 2,3-acetonide of rhamnonolactone allows inversion of configuration at C4 and/or C5 of rhamnose to give 6-deoxy-d-allose, 6-deoxy-d-gulose and 6-deoxy-l-talose. Highly crystalline 3,5-benzylidene rhamnonolactone gives easy access to l-quinovose (6-deoxy-l-glucose), l-olivose and rhamnose analogue with C2 azido, amino and acetamido substituents. Electrophilic fluorination of rhamnal gives a mixture of 2-deoxy-2-fluoro-l-rhamnose and 2-deoxy-2-fluoro-l-quinovose. Biotechnology provides access to 6-deoxy-l-altrose and 1-deoxy-l-fructose., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Ease of separation of petrol-soluble acetonides derived from the triacetonide of methyl glucoheptonate allows scalable syntheses of rare sugars containing the l-gluco or d-gulo structural motif with any oxidation level at the C6 or C1 position of the hexose, usually without chromatography: meso-d-glycero-d-guloheptitol available in two steps is an ideal entry point for the study of the biotechnological production of heptoses.

Reverse aldol opening renders amides of 3-hydroxyazetidinecarboxylic acids (3-OH-Aze) unstable above pH 8. Aze, found in sugar beet, is mis-incorporated for proline in peptides in humans and is associated with multiple sclerosis and teratogenesis. Aze-containing peptides may be oxygenated by prolyl hydroxylases resulting in potential damage of the protein by a reverse aldol of the hydroxyazetidine; this, rather than changes in conformation, may account for the deleterious effects of Aze. This paper describes the synthesis of 3-fluoro-Aze amino acids as hydroxy-Aze analogues which are not susceptible to aldol cleavage. 4-(Azidomethyl)-3-fluoro-Aze and 3,4-difluoroproline are new peptide building blocks. trans,trans-2,4-Dihydroxy-3-fluoroazetidine, an iminosugar, inhibits the growth of pancreatic cancer cells to a similar degree as gemcitabine.

Addition of human milk oligosaccharides (HMO) to baby foods may protect infants from disease. As many simple HMOs are fucosylated this is likely to increase the demand for L-fucose as a synthetic building block. Any chemical synthesis must be cheap to compete with a biotechnological process. Acetonide is the only protecting group we have used in this new synthesis of L-fucose from vitamin C in 27% overall yield (purification by recrystallization; no chromatography required in the entire sequence).

All 16 stereoisomeric N-methyl 5-(hydroxymethyl)-3,4-dihydroxyproline amides have been synthesized from lactones accessible from the enantiomers of glucuronolactone. Nine stereoisomers, including all eight with a (3R)-hydroxyl configuration, are low to submicromolar inhibitors of β-N-acetylhexosaminidases. A structural correlation between the proline amides is found with the ADMDP-acetamide analogues bearing an acetamidomethylpyrrolidine motif. The proline amides are generally more potent than their ADMDP-acetamide equivalents. β-N-Acetylhexosaminidase inhibition by an azetidine ADMDP-acetamide analogue is compared to an azetidine carboxylic acid amide. None of the amides are good α-N-acetylgalactosaminidase inhibitors.

The scarcity and expense of access to L-sugars and other rare sugars have prevented the exploitation of their biological potential; for example D-psicose, only recently available, has been recognized as an important new food. Here we give the definitive and cheap synthesis of 99.4% pure L-glucose from D-glucose which requires purification of neither intermediates nor final product other than extraction into and removal of solvents; a simple crystallization will raise the purity to >99.8%., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

X-ray crystallography firmly established the relative stereochemistry of the title compound, C16H20N2O3. The acetonide ring adopts an envelope conformation with one of the O atoms as the flap and the piperidine ring adopts a slightly twisted boat conformation. The absolute configuration was determined by use of d-ribose as the starting material. The compound exists as O-H⋯O hydrogen-bonded chains of mol-ecules running parallel to the b axis.

Crystal structures were obtained for the two C2 epimeric azido-γ-lactones 2-azido-2-deoxy-3,5:6,7-di-O-isopropylidene-d-glycero-d-ido-heptono-1,4-lactone and 2-azido-2-deoxy-3,5:6,7-di-O-isopropylidene-d-glycero-d-gulo-heptono-1,4-lactone prepared from kinetic and thermodynamic azide displacements of a triflate derived from d-glucoheptonolactone. Azido-γ-lactones are very useful intermediates in the synthesis of iminosugars and polyhydroxylated amino acids. In this study two epimeric azido-heptitols allow biotechnological transformations via Izumoring techniques to 8 of the 16 possible homonojirimycin analogues, 5 of which were isolated pure because of the lack of stereoselectivity of the final reductive amination. A side-by-side glycosidase inhibition profile of 11 of the possible 16 HNJ stereoisomers derived from d-glucose and d-mannose is presented.

The synthesis from l-arabinose of an azetidine analogue of 6,7-diepicastanospermine and its glycosidase inhibition profile are described., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The Ho crossed aldol condensation provides access to a series of carbon branched iminosugars as exemplified by the synthesis of enantiomeric pairs of isoDMDP, isoDGDP, and isoDAB, allowing comparison of their biological activities with three linear isomeric natural products DMDP, DGDP, and DAB and their enantiomers. L-IsoDMDP [(2S,3S,4R)-2,4-bis(hydroxymethyl)pyrrolidine-3,4-diol], prepared in 11 steps in an overall yield of 45% from d-lyxonolactone, is a potent specific competitive inhibitor of gut disaccharidases [K(i) 0.081 μM for rat intestinal maltase] and is more effective in the suppression of hyperglycaemia in a maltose loading test than miglitol, a drug presently used in the treatment of late onset diabetes. The partial rescue of the defective F508del-CFTR function in CF-KM4 cells by L-isoDMDP is compared with miglustat and isoLAB in an approach to the treatment of cystic fibrosis.

The formation from D-glucose of both enantiomers of 2,4-dideoxy-2,4-iminoribonic acid is the first chemical synthesis of unprotected 3-hydroxyazetidine carboxylic acids. The long-term stability of 3-hydroxyazetidine amides is established at acidic and neutral pH and implies their value as non-proteinogenic amino acid components of peptides, providing medicinal chemists with a new class of peptide isosteres. The structure of N,3-O-dibenzyl-2,4-dideoxy-2,4-imino-D-ribonic acid was established by X-ray crystallographic analysis. An N-methylazetidine amide derivative is a specific inhibitor of β-hexosaminidases at the micromolar level, and is only the second example of potent inhibition of any glycosidase by an amide of a sugar amino acid related to an iminosugar., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The absolute stereochemistry of the title compound, C(9)H(15)NO(7), was determined from the use of d-glucuronolactone as the starting material. The compound crystallizes as the zwitterion. The five-membered ring adopts an envelope conformation with the -CH(2)OH-substituted C atom forming the flap. An intramolecular N-H⋯O hydrogen-bond occurs. In the crystal, the compound exists as a three-dimensional O-H⋯O intermolecular hydrogen-bonded network with each mol-ecule acting as a donor and acceptor for four hydrogen bonds.

The enantiomers of glucuronolactone are excellent chirons for the synthesis of the 10 stereoisomeric 2,5-dideoxy-2,5-iminohexitols by formation of the pyrrolidine ring by nitrogen substitution at C2 and C5, with either retention or inversion of configuration; the stereochemistry at C3 may be adjusted during the synthesis to give seven stereoisomers from each enantiomer. A definitive side-by-side comparison of the glycosidase inhibition of a panel of 13 glycosidases showed that 8 of the 10 stereoisomers showed significant inhibition of at least one glycosidase.

Ring closure of a 3,5-di-O-triflate derived from D-altrose with benzylamine allowed the formation of both monocyclic and bicyclic azetidine analogues of swainsonine.

X-ray crystallography confirmed the formation, structure and relative stereochemistry of the title compound, C(15)H(19)NO(3), which contains a sterically congested four-membered azetidine ring system. The absolute configuration was determined by the use of l-arabinose as the starting material.

The six-membered boronate ester ring of the title compound, C(13)H(16)BNO(6), adopts an envelope conformation with the C atom bearing the dimethyl substituents at the flap. The O-B-C-C torsion angles between the boronate group and the benzene ring are 72.5 (2) and 81.0 (2)°. The 4-nitro-benzoate unit adopts a slightly twisted conformation, with dihedral angles between the benzene ring and the nitrate and methyl ester groups of 17.5 (2) and 14.4 (3)°, respectively. In the crystal, inversion-related pairs of mol-ecules show weak π-π stacking inter-actions [centroid-centroid distance = 4.0585 (9) Å and inter-planar spacing = 3.6254 (7) Å].

X-ray crystallography firmly established the relative stereochemistry of the title compound, C(17)H(22)N(2)O(3). The absolute configuration was determined by use of 2-C-methyl-d-ribonolactone as the starting material. The compound exists as O-H⋯N hydrogen-bonded chains of mol-ecules running parallel to the a-axis.

Although there are 32 6-azidoheptitols, there are only 16 homonojirimycin (HNJ) stereoisomers. Two epimeric azidoalditols derived from d-mannose allow the synthesis in water of eight stereoisomers of HNJ., (© 2012 American Chemical Society)

Primary amines with either 3,5-di-O-ditriflates of α-furanosides or 2,4-di-O-triflates of β-pyranosides form bicyclic azetidines in high yield., (© 2012 American Chemical Society)

Efficient ring closure of stable crystalline 3,5-di-O-triflates of pentofuranosides with amines to form azetidines allowed preliminary evaluation of four-ring iminosugars as glycosidase inhibitors; significant and specific inhibition of nonmammalian α-glucosidases is shown by L-xylo- and L-arabino-iminosugar azetidines., (© 2011 American Chemical Society)

X-ray crystallography unequivocally confirmed the stereochemistry of the 2-C-methyl group in the title mol-ecule, C(10)H(16)O(5), in which the 1,5-lactone ring exists in a boat conformation. The absolute stereochemistry was determined by the use of d-ribose in the synthesis. The crystal exists as O-H⋯O hydrogen bonded chains of mol-ecules running parallel to the a axis with each mol-ecule acting as a donor and acceptor for one hydrogen bond.

The structure determination confirms the stereochemistry of the title compound, C(12)H(17)NO(3), which contains a four-membered azetidine ring system. The absolute configuration was determined by the use of d-glucose as the starting material. In the crystal, O-H⋯O and O-H⋯N hydrogen bonds link the mol-ecules into layers in the ab plane.

The enantiomers of tagatose are converted to L-DGJ [a noncompetitive inhibitor of human lysosome α-galactosidase A (α-Gal A), K(i) 38.5 μM] and DGJ [a competitive inhibitor of α-Gal A, K(i) 15.1 nM] in 66% yield. L-DGJ and DGJ provide the first examples of pharmacological chaperones that (a) are enantiomeric iminosugars and (b) have synergistic activity with implications for the treatment of lysosomal storage disorders and other protein deficiencies., (© 2011 American Chemical Society)

The syntheses of 4-C-Me-DAB [1,4-dideoxy-1,4-imino-4-C-methyl-d-arabinitol] from l-erythronolactone and of 4-C-Me-LAB [from d-erythronolactone] require only a single acetonide protecting group. The effect of pH on the NMR spectra of 4-C-Me-DAB [pK(a) of the salt around 8.4] is discussed and illustrates the need for care in analysis of both coupling constants and chemical shift. 4-C-Me-DAB (for rat intestinal sucrase K(i) 0.89 μM, IC(50) 0.41 μM) is a competitive - whereas 4-C-Me-LAB (for rat intestinal sucrase K(i) 0.95 μM, IC(50) 0.66 μM) is a non-competitive - specific and potent α-glucosidase inhibitor. A rationale for the α-glucosidase inhibition by DAB, LAB, 4-C-Me-DAB, 4-C-Me-LAB, and isoDAB - but not isoLAB - is provided. Both are inhibitors of endoplasmic reticulum (ER) resident α-glucosidase I and II.

Alpha-Triflates of gamma-lactones with potassium carbonate in methanol give efficient contraction of the ring to oxetane-1-carboxylates in which the oxygen substituent at C(3) of the oxetane is predominantly trans to the carboxylate at C(2), regardless of the stereochemistry of the starting triflate. The limitations of the procedure are discussed and compared with analogous reactions for the preparation of THF carboxylates. The potential of the contraction in the preparation of oxetane nucleosides (such as oxetanocin) and oxetane sugar amino acids (analogues of oxetin) as peptidomimetics with predisposition to form secondary structural motifs is illustrated.

Reaction of 3-O-benzyl-1,2-O-isopropyl-idene-α-xylo-pentodialdo-1,4-furan-ose with N,N-diethyl-2-(dimethyl-sulfuranil-idene)acetamide gave stereoselectively an ep-oxy-amide, which was regioselectively opened by NaN(3) in dimethyl formamide to give the title compound, C(21)H(30)N(4)O(6). X-ray crystallography confirmed the relative stereochemistry of the title compound and the absolute configuration was determined by the use of d-glucose as the starting material. There are two mol-ecules in the asymmetric unit (Z' = 2). The crystal structure consists of two types of chains of O-H⋯O hydrogen-bonded mol-ecules running parallel to the b axis, with each mol-ecule acting as a donor and acceptor of one hydrogen bond.

The crystal structure unequivocally confirms the relative stereochemistry of the title compound, C(6)H(13)FO(5) [6-de-oxy-6-fluoro-d-galactitol or (2S,3R,4R,5S)-6-fluoro-hexane-1,2,3,4,5-penta-ol]. The absolute stereochemistry was determined from the use of d-galactose as the starting material. In the crystal, the molecules are linked by O-H⋯O and O-H⋯F hydrogen bonds, forming a three-dimensional network with each mol-ecule acting as a donor and acceptor for five hydrogen bonds.

The crystal structure unequivocally confirms the relative stereochemistry of the title compound, C(6)H(11)FO(5). The absolute stereochemistry was determined by the use of d-galactose as the starting material. The compound exists as a three-dimensional O-H⋯O hydrogen-bonded network with each mol-ecule acting as a donor and acceptor for four hydrogen bonds.

The relative stereochemistry of the title compound, C(10)H(15)N(3)O(5), was confirmed by the crystal structure determin-ation. The absolute configuration was determined from the use of d-lyxonolactone as the starting material. The six-membered ring adopts a boat conformation with the larger azide group, rather than the methyl group, in the bowsprit position. In the crystal structure, a bifurcated inter-molecular O-H⋯O/O-H⋯N hydrogen bond links mol-ecules into chains running parallel to the b axis.

X-ray crystallography defines the relative configuration at the three-stereogenic centres in the title compound N-benzyl-l-XYLNAc, C(14)H(20)N(2)O(3). The five-membered pyrrolidine ring adopts an envelope conformation with the N atom lying out of the plane of the other four atoms. In the crystal structure, inter-molecular O-H⋯O, N-H⋯O and O-H⋯N hydrogen bonds link the mol-ecules into chains along [100]. The carbonyl group O atom acts as an acceptor for a bifurcated hydrogen bond. The absolute configuration is determined by the use of l-glucuronolactone as the starting material for the synthesis.

The crystal structure of the title compound, C(12)H(18)N(2)O(8), exists as O-H⋯O hydrogen-bonded layers of mol-ecules running parallel to the ab plane. Each mol-ecule is a donor and acceptor for six hydrogen bonds. The absolute stereochemistry was determined by the use of d-glucuronolactone as the starting material.

In the title compound, C(13)H(21)N(3)O(6), the six-membered ring adopts a twist-boat conformation with the azide group in the bowsprit position. The azide group is disordered over two sets of sites in a 0.642 (10):0.358 (10) ratio. The crystal structure consists of O-H⋯O hydrogen-bonded trimer units. The absolute configuration was determined from the use of d-mannose as the starting material.

X-ray crystallography unequivocally confirmed the stereochemistry of the 2-C-methyl group in the title mol-ecule, C(10)H(16)O(6), in which the 1,5-lactone ring exists in a boat conformation. The use of d-galactose in the synthesis determined the absolute stereochemistry. The crystal exists as O-H⋯O hydrogen-bonded layers in the ab plane, with each mol-ecule acting as a donor and acceptor for two hydrogen bonds.

X-Ray crystallography unequivocally determined the stereochemistry of the thymine base in the title compound, C(14)H(18)N(2)O(7). The absolute stereochemistry was determined from the use of d-ribose as the starting material. There are two independent mol-ecules in the asymmetric unit (Z' = 2) which exist as N-H⋯O hydrogen-bonded pairs in the crystal structure.

The crystal structure of the title compound, C(6)H(11)NO(5), establishes the relative configuration at the four stereogenic centres; the absolute configuration is determined by the use of d-glucuronolactone as the starting material for the synthesis. Mol-ecules are linked by inter-molecular O-H⋯O and N-H⋯O hydrogen bonds into a three-dimensional network, with each mol-ecule acting as a donor and acceptor for five hydrogen bonds.

The chemical name of the title compound in the paper by Jenkinson, Fenton, Booth, Fleet & Watkin [Acta Cryst. (2009), E65, o610-o611] is corrected.[This corrects the article DOI: 10.1107/S1600536809006357.].

The crystal structure of the title compound, C(13)H(14)O(5), establishes (i) the (S) - rather than (R) - configuration at the acetal carbon and (ii) that both the acetal and the lactone form five- rather than six-membered rings; the absolute configuration is determined by the use of 2-C-methyl-d-ribono-1,4-lactone as the starting material. The compound consists of hydrogen-bonded chains of mol-ecules running along the a axis; there are no unusual packing features. Only classical hydrogen bonding has been considered.

The title mol-ecule, C(7)H(15)NO(5), the major product from selective enzymatic oxidation followed by hydrogeno-lysis of the corresponding azido-heptitol, was found by X-ray crystallography to exisit in a chair conformation with three axial hydroxyl groups. One of the hydroxymethyl groups is disordered over two sets of sites in a 0.590 (3):0.410 (3) ratio. In the crystal, O-H⋯O, O-H⋯(O,O), O-H⋯N and N-H⋯O hydrogen bonding occurs.

The N-alkylated deoxynojirimycin compound, N-(6'-(4''-azido-2''-nitrophenylamino)hexyl)-1-deoxynojirimycin (6) was synthesised as a potential photoaffinity probe for endoplasmic reticulum (ER) alpha-glucosidases I and II. Surprisingly this compound was a highly potent inhibitor of alpha-glucosidase I (IC(50), 17 nM) in an in vitro assay and proved equally effective at inhibiting cellular ER glucosidases, as determined by a free oligosaccharide (FOS) analysis. A modest library of compounds was synthesised to obtain structure-activity information by variation of the N-alkyl chain length and modifications to the azido-nitrophenyl group. All of these compounds failed to improve on the efficacy of compound 6, but most showed greater enzyme inhibitory potency than N-butyl-deoxynojirimycin (NB-DNJ), a pharmacological agent that has been evaluated for the treatment of several viruses for which infectivity is dependent on host cell glycosylation.

X-ray crystallography confirmed the structure of the title triazole, C(11)H(15)N(3)O(5), formed from a single-step reaction of a sugar azide with a brominated ylid. The absolute configuration was determined by the use of d-ribose as the starting material. The six-membered ring is in a half-chair conformation. The crystal structure exists as chains of O-H⋯O hydrogen-bonded moleclues running parallel to the b axis.

X-ray crystallography unequivocally confirmed the stereochemistry of the C atom at position 2 in the carbon scaffold of the title mol-ecule, C(10)H(18)O(4). The pyran-ose ring exists in a chair conformation with the methyl group on the C atom in the 2 position in an equatorial configuration. The absolute stereochemistry was determined from the starting material. The crystal structure consists of O-H⋯O hydrogen-bonded chains of mol-ecules running parallel to the b axis.

X-ray crystallographic analysis has established that the major product from the protection of d-glucoronolactone with benzaldehyde is (1S)-1,2-O-benzyl-idene-α-d-glucurono-6,3-lactone, C(13)H(12)O(6), rather than the R epimer. The crystal structure exists as O-H⋯O hydrogen-bonded chains of mol-ecules lying parallel to the a axis. The absolute configuration was determined by the use of d-glucuronolactone as the starting material.

The reaction of 5-azido-5-de-oxy-2,3-O-isopropyl-idene-2-C-methyl-d-ribose with N,N-diethyl-2-(dimethyl-sulfuranyl-idene)acetamide gave the title compound, C(15)H(26)N(4)O(5), as the major product arising from initial formation of an epoxide which was subsequently opened by intra-molecular attack of the free 4-hydroxyl group. X-ray crystallography confirmed the relative stereochemistry of the title compound and the absolute configuration was determined by the use of d-ribose as the starting material. The crystal structure contains chains of mol-ecules running parallel to the a axis, being linked by weak bifurcated O-H⋯(N,N) hydrogen bonds.

X-ray crystallography unequivocally showed that protection of the free hydroxyl group of 3,5-O-benzyl-idene-d-lyxono-1,4-lactone with diphenyl-diazo-methane proceeded with retention of configuration to give the title compound, C(25)H(22)O(5). The crystal structure consists of layers of inter-locked mol-ecules lying parallel to the a axis.