New Glycomimetics: Anomeric Sulfonates, Sulfenamides, and Sulfonamides

Direct Synthesis of Glycosyl Chlorides from Thioglycosides

Reported herein is a new method for the direct synthesis of glycosyl chlorides from thioglycosides using sulfuryl chloride at rt. A variety of thioglycosides and thioimidates could be used as substrates. Both acid- and base-sensitive protecting groups were found compatible with these reaction conditions. Preliminary investigation of the reaction mechanism indicates chlorination of the leaving group at the anomeric sulfur as the key step of the reaction.

Glycosyl disulfides: importance, synthesis and application to chemical and biological systems

This review explores methodologies for the preparation of glycosyl disulfides, their utility as intermediates in carbohydrate synthesis, and evaluates their biological impact in glycoscience and beyond.

Thio-click reaction of 2-deoxy-exo-glycals towards new glycomimetics: stereoselective synthesis of C-2-deoxy-d-glycopyranosyl compounds

Photoinitiated addition of thiols to 2-deoxy-exo-glycals obtained from endo-glycals of d-arabino, d-lyxo, d-erythro and d-threo configurations resulted in highly regio- and stereoselective formation of glycosylmethyl sulfide type glycomimetics.

Straightforward S-S Bond Formation via the Oxidation of S-Acetyl by Iodine in the Presence of N-Iodosuccinimide

Straightforward S-S bond formation via the oxidation of S-acetyl group by iodine was reported here. The reaction was further applied in the synthesis of per-O-acetylated glycosyl disulfides. These studies demonstrated great improvement in reaction rate, yield, and general convenience in the presence of N-iodosuccinimide. Furthermore, selectively deacetylated glycosyl thiols were obtained in high yields when these per-O-acetylated glycosyl disulfides were reduced with tris(2-carboxyethyl)-phosphine (TCEP). Our method supplied an efficient way to obtain both per-O-acetylated glycosyl disulfides and per-O-acetylated glycosyl thiols in which the sulfur group was located at any position.

Synthesis of Sulfo-Sialic Acid Analogues: Potent Neuraminidase Inhibitors in Regards to Anomeric Functionality

The design, synthesis and application of N-acetylneuraminic acid-derived compounds bearing anomeric sulfo functional groups are described. These novel compounds, which we refer to as sulfo-sialic acid analogues, include 2-decarboxy-2-deoxy-2-sulfo-N-acetylneuraminic acid and its 4-deoxy-3,4-dehydrogenated pseudoglycal. While 2-decarboxy-2-deoxy-2-sulfo-N-acetylneuraminic acid contains no further modifications of the 2-deoxy-pyranose ring, it is still a more potent inhibitor of avian-origin H5N1 neuraminidase (NA) and drug-resistant His275Tyr NA as compared to the oxocarbenium ion transition state analogue 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. The sulfo-sialic acid analogues described in this report are also more potent inhibitors of influenza NA (up to 40-fold) and bacterial NA (up to 8.5-fold) relative to the corresponding anomeric phosphonic acids. These results confirm that this novel anomeric sulfo modification offers great potential to improve the potency of next-generation NA inhibitors including covalent inhibitors.

Convenient preparation of thioglycomimetics: S-glycosyl sulfenamides, sulfinamides and sulphonamides

S-Glycosyl sulfenamide derivatives were rapidly prepared from glycosyl thiols using N-bromosuccinimide or N-chlorosuccinimide. Sulfenamide derivatives were oxidized to corresponding sulfinamides and sulfonamides.

Novel strategies for the synthesis of unsymmetrical glycosyl disulfides

Novel strategies for the efficient synthesis of unsymmetrical glycosyl disulfides are reported. Glycosyl disulfides are increasingly important as glycomimetics and molecular probes in glycobiology. Sialosyl disulfides are synthesised directly from the chlorosialoside Neu5Ac2Cl, proceeding via a thiol-disulfide exchange reaction between the sialosyl thiolate and symmetrical disulfides. This methodology was adapted and found to be successfully applicable to the synthesis of unsymmetrical glucosyl disulfides under mild conditions.

Synthesis and anti-mycobacterial activity of glycosyl sulfamides of arabinofuranose

A series ofarabino N-glycosyl sulfamides, forced to adopt the furanose form by removal of the 5-hydroxyl group, were synthesised as putative isosteric mimics of decaprenolphosphoarabinose, the donor processed by arabinosyltransferases during mycobacterial cell wall assembly.

Photoinitiated hydrothiolation of pyranoid exo-glycals: the d-galacto and d-xylo cases

Radical-mediated addition reactions of thiols to O-peracetylated exo-galactal and exo-xylal with 2,2-dimethoxy-2-phenylacetophenone as the photoinitiator resulted in high yielding formation of the corresponding β-d-glycopyranosylmethyl-sulfide derivatives (2,6-anhydro-1-deoxy-1-S-substituted-1-thio-alditols) with exclusive regio- and very high stereoselectivity, including disaccharide mimicks with Gly-CH2-S-Gly scaffolds.

Unexpected furanose/pyranose equilibration of N-glycosyl sulfonamides, sulfamides and sulfamates

Arabino N-glycosyl sulfamides, sulfonamides and sulfamates convert from the furanose to the thermodynamically preferred pyranose form in aqueous solution.

Stereocontrolled 1-S-glycosylation and comparative binding studies of photoprobe-thiosaccharide conjugates with their O-linked analogs

The use of thioglycosides and other glycan derivatives with anomeric sulfur linkages is gaining increasing interest, both in synthesis and in various biological contexts. Herein, we demonstrate the occurrence and circumvention of anomerization during 1-S-glycosylation reactions, and present highly efficient and stereocontrolled syntheses of a series of photoprobe-thiosaccharide conjugates. Mutarotation of glycosyl thiols proved to be the origin of the anomeric mixtures formed, and kinetic effects could be used to circumvent anomerization. The synthesized carbohydrate conjugates were then evaluated by both solution- and solid-phase-based techniques. Both binding results showed that the S-linked glyco-sides interact with their cognate lectins comparably to the corresponding O-analogs in the present cases, thus demonstrating the reliability of the solid-support platform built upon our photo-initiated carbohydrate immobilization method for probing protein bindings, and showing the potential of combining these two means for studying carbohydrate-protein interactions.

β-D-Arabinosyl 1-C-sulfonic acid. J Sulphur Chem 2013;34:33-37. [PMID: 28966658 DOI: 10.1080/17415993.2012.706814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

A short synthetic route to β,d-arabinofuranosyl 1-C-sulfonic acid (7), a possible biomimetic for the arabinofuranosyl anomeric phosphate, is described. The furanosyl 1-C-sulfonate was prepared by buffered DMDO oxidation of an S-acetyl-1-thio-β-arabinofuranose derivative. Deprotection under mild conditions allowed isolation of the free sulfonic acid without desulfonylation.

New class of biodegradable polymers formed from reactions of an inorganic functional group

Although numerous small molecules have been synthesized with sulfenamide bonds (R(2)N-SR), this is the first report of the synthesis of polysulfenamides. These polymers are readily synthesized at room temperature using secondary diamines and dithiosuccinimides. The dithiosuccinimides were readily synthesized in one step by the reaction of dithiols such as HS(CH(2))(6)SH with N-chlorosuccinimide. The resulting dithiosuccinimides were either recrystallized or readily purified by chromatography on silica gel and required no special handling. The conversions of polymerization ranged from 95 to 98%, and the molecular weights of the polymer reached as high as 6,300 g mol(-1). The sulfenamide bond was very stable in organic solvents, and no degradation was observed under atmospheric conditions in C(6)D(6) for 30 days. In contrast, the sulfenamide bond readily decomposed in less than 12 h in D(2)O. Polysulfenamides were fabricated into micron-sized particles loaded with dye and endocytosed into JAWSII immature dendritic and HEK293 cells. Polysulfenamides represent a new class of polymers that are readily synthesized, stable in aprotic solvents, and readily degrade in water.

A remarkable cyclization of TADDOL-bisthioacetate under oxidative conditions

Abstract

Attempted oxidation of a TADDOL-derived bisthioacetate resulted in a rather unexpected and remarkable cyclization and deprotection reaction, giving a thiolane-1,1-dioxide as the main product. Systematic in situ ESI-HRMS studies revealed a bicyclic, highly acid labile key intermediate of this reaction. Supported by force field calculations, the high sensitivity of this intermediate was judged to be due to the formation of a highly strained trans-configured bicyclo[3.3.0]skeleton.

Graphical abstract

Psammaplin Metabolites New and Old: An NMR Study Involving Chiral Sulfur Chemistry

The new metabolite psammaplin N (8) that contains a sulfoxide moiety has been isolated together with psammaplins A (1), I (4a), and J (2) from a specimen of the marine sponge Aplysinella rhax (order Verongida family Aplysinidae) collected in South East Queensland. An NMR study on psammaplin J reveals its facile conversion to psammaplins A and I when exposed to methanol.

Crystal and molecular structures of diglycosyl disulfide derivatives

The crystal and molecular structures of S-(2,3,4,6-tetra-O-acetyl-beta-d-glucopyranosyl)-S'-(2,3,4,6-tetra-O-acetyl-beta-d-galactopyranosyl)disulfide (1) and the mono-sulfoxide (3) of bis(2,3,4,6-tetra-O-acetyl-beta-d-glucopyranosyl)disulfide (2) are described. Comparison of 2 and 3, containing -S-S- and -S-S(O)- bonds, respectively, allows to delineate structural differences brought about by the different oxidation states of one of the sulfur atoms in carbohydrate disulfides.