Glycosyl Cyanides Research Articles

Stereoselective Synthesis of Glycosyl Cyanides by TMSOTf‐Mediated Ring Opening of 1,6‐Anhydro Sugars

AbstractWe describe herein a convenient access to glycosyl cyanides by way of TMSCN ring opening of 1,6‐anhydro sugars mediated by TMSOTf with modest to high stereocontrol in the D‐gluco, D‐galacto and D‐manno series. The reaction is tolerant to various functional groups including free alcohols, alkenes and terminal alkynes. The straightforward synthesis of a constrained analogue of 1‐cyano‐D‐glucal with a 3,6‐anhydro sugar framework is presented to illustrate the interest of the TMSCN ring‐opening reaction.

The first general synthesis of 2-C-(β-d-glycopyranosyl)pyrimidines and their evaluation as inhibitors of some glycoenzymes

The first systematic study on the synthesis of 2-C-(β-d-glycopyranosyl)pyrimidines either from amidine A or glycosyl cyanides B and 1,3-dicarbonyl compounds.

ChemInform Abstract: Chemoselective Hydration of Glycosyl Cyanides to C‐Glycosyl Formamides Using Ruthenium Complexes in Aqueous Media.

AbstractA wide variety of glycosyl cyanides such as (I) are converted into the corresponding formamide derivatives in water or water/NMP mixtures as the solvent.

Chemoselective hydration of glycosyl cyanides to C-glycosyl formamides using ruthenium complexes in aqueous media

[RuCl2(DMSO)4] in the presence of N-benzylated 1,3,5-triaza-7-phosphaadamantane efficiently catalyzed the hydration of glycosyl cyanides to the corresponding formamide derivatives in water or water–N-methylpyrrolidone solvent mixtures at 105°C. O-Acetyl, O-benzoyl, and O-benzyl protecting groups, anomeric bromide and azide substituents as well as double bonds were shown to be compatible with these reaction conditions.

Preparation of 1-C-glycosyl aldehydes by reductive hydrolysis

Reductive hydrolysis of various protected glycosyl cyanides was carried out using DIBAL-H to form aldimine alane intermediates which were then hydrolyzed under mildly acidic condition to provide the corresponding aldehyde derivatives. While 1-C-formyl glycal and 2-deoxy glycosyl derivatives were stable during isolation and storage 1-C-glycosyl formaldehydes in the gluco, galacto and manno series were sensitive and decomposition occurred by 2-alkyloxy elimination. A one-pot method using N,N′-diphenylethylenediamine to trap these aldehydes in stable form was developed. Reductive hydrolysis of glycosyl cyanides offers valuable aldehyde building blocks in a convenient way which can be applied in the synthesis of complex C-glycosides.

ChemInform Abstract: Thermal C-Glycosylation of D-Glucal with Trimethylsilyl Cyanide.

Abstract The treatment of 3,4,6-tri- O -acetyl- d -glucal and unprotected d -glucal with trimethylsilyl cyanide, under thermal conditions in the absence of catalyst, afforded the corresponding 2,3-unsaturated glycosyl cyanides in high yield.

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.

A Facile and General Entry to C‐Glycosyl (R)‐ and (S)‐β‐Amino Acid Pairs from Glycosyl Cyanides Through Enamino Ester Intermediates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

A Facile and General Entry toC-Glycosyl (R)- and (S)-β-Amino Acid Pairs from Glycosyl Cyanides through Enamino Ester Intermediates

Four O-perbenzylated glycosyl cyanides (α- and β-d-mannopyranosyl, α-d-galactopyranosyl, and α-d-arabinofuranosyl) were converted by treatment with BrCH2CO2Et/Zn in THF at reflux (Blaise-Kishi reaction) into the corresponding C-glycosyl β-en­amino esters which in turn were reduced by NaBH(OAc)3 to give four pairs of C-glycosyl (R)- and (S)-β-amino esters.

Expeditious synthesis of sulfoazetidine spiro- C-glycosides from ketose acetals

Pyranoid and furanoid spiro- N-mesyl azetidines, a new type of water-soluble spiro- C-nucleoside, have been prepared from easily available sugar spiroacetals (or glycosyl cyanides). The synthetic pathway involves opening of the acetalic ring with trimethylsilylcyanide, reduction, formation of an N, O-dimesylate, cyclization with sodium hydride in anhydrous DMF, and O-deprotection.

A Novel Stereospecific Synthesis of Glycosyl Cyanides from 1,2‐O‐Sulfinyl Derivatives.

AbstractFor Abstract see ChemInform Abstract in Full Text.

A Novel Stereospecific Synthesis of Glycosyl Cyanides from 1,2-O-Sulfinyl Derivatives

[reaction: see text] An efficient synthesis of 1,2-trans-glycosyl cyanides via 1,2-O-sulfinyl monosaccharides is described. Such S(N)2-type displacements at the anomeric center are stereospecific and are best performed with sodium cyanide in the presence of ytterbium triflate. Significantly, the resulting 1,2-trans-glycosyl cyanides have a free hydroxyl group at C-2 ready for further modification.

Bi(OTf)3as Novel and Efficient Catalyst for the Stereoselective Synthesis ofC-Pseudoglycals

D-Glycals undergo smoothly allylic rearrangement with allyltrimethylsilane and trimethylsilyl cyanide in the presence of catalytic amount of bismuth triflate to afford the corresponding 2,3-unsaturated allyl glycosides and glycosyl cyanides in excellent yields with high α-selectivity.

C-glycosylmethylene carbenes: synthesis of anhydro-aldose tosylhydrazones as precursors; generation and a new synthetic route to exo-glycals.

Acylated anhydro-aldononitriles (glycosyl cyanides) were transformed into anhydro-aldose tosylhydrazones by Raney-nickel reduction in the presence of tosylhydrazine in a one-pot reaction. The configuration of the C=N double bond in these hydrazones was E as proven by 15N-1H coupling constants as well as X-ray crystallography. Thermolysis in refluxing 1,4-dioxane of the sodium salts of the tosylhydrazones obtained by sodium hydride (generally 10 eq.) resulted in the formation of anhydro-1-deoxy-ald-1-enitols (exo-glycals). "Dimeric" N-glycosylmethyl anhydro-aldose tosylhydrazones could also be isolated when the use of less base caused incomplete deprotonation of the starting compounds. This two-step procedure constitutes a novel, reasonably short synthetic pathway to acylated exo-glycals from the readily available glycosyl cyanides.

Palladium-charcoal-catalyzed reduction of tri-O-acetyl-beta-L-fucopyranosyl cyanide: a route to small cluster oligosaccharide mimetics (SCOMs).

[reaction: see text] Synthesis of glycosyl cyanides was optimized with a new catalyst system. Reduction of tri-O-acetyl-beta-L-fucopyranosyl cyanide with Pd-hydrogen, in the presence of Ac(2)O and Boc(2)O, gave N-protected-mono- and -di-(2,3,4-tri-O-acetyl-beta-L-fucopyranosylmethyl)-amines, which allow for the syntheses of small cluster oligosaccharide mimetics of fucopyranosylomethyl-substituted ureas. From di-(2,3,4-tri-O-acetyl-beta-L-fucopyranosylmethyl) amine was also prepared a carbamoyl chloride as a potentially useful synthon for preparation of more complex C-glycosidic conjugates.

Stereoselective C-glycosidation of unprotected D-glycals with trimethylsilyl cyanide.

Unprotected glycals reacted with trimethylsilyl cyanide in the presence of a catalytic amount of a palladium compound to yield the 2,3-unsaturated glycosyl cyanides in high yield and in alpha-selectivity.

InBr3-Catalyzed Ferrier Rearrangement: An Efficient Synthesis of C-Pseudoglycals

Glycals react smoothly with silyl nucleophiles such as allyltrimethylsilane, trimethylsilyl cyanide and trimethylsilyl azide in the presence of a catalytic amount of indium tribromide to give the corresponding 2,3-unsaturated allyl glycosides, glycosyl cyanides and glycosyl azides in excellent yields with high α-selectivity.

ChemInform Abstract: Sc(OTf)3‐Catalyzed C‐Glycosidation of Glycals: A Facile Synthesis of Allyl Glycosides, Glycosyl Cyanides and Glycosyl Azides.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Preparation of 3,5-bis-(β- d -glycopyranosyl)-1,2,4-thiadiazoles from C -(β- d -glycopyranosyl)thioformamides

Abstract Acylated C-glycopyranosyl thioformamides of d -gluco, d -galacto, and d -xylo configuration were obtained by treating the corresponding glycosyl cyanides with hydrogen sulfide in the presence of triethylamine. The thioformamides gave 3,5-bis-(β- d -glycopyranosyl)-1,2,4-thiadiazoles in reactions with potassium bromate and sodium dithionite in dichloromethane–water biphasic solvent mixture. Deprotected derivatives were prepared by Zemplen deacylation.

Sc(OTf) 3-catalyzed C-glycosidation of glycals: a facile synthesis of allyl glycosides, glycosyl cyanides and glycosyl azides

The treatment of glycals with allyltrimethylsilane, trimethylsilyl cyanide and trimethylsilyl azide in the presence of catalytic amounts of Sc(OTf) 3 gave the corresponding 2,3-unsaturated allyl glycosides, glycosyl cyanides and glycosyl azides in excellent yields with high α-selectivity.