A new 6-C-alkylation from an alkyl mannofuranoside 5,6-cyclic sulfate

Methyl 6-C-alkyl-6-deoxy-alpha-D-mannofuranoside derivatives have been synthesized from methyl 2,3-O-isopropylidene-5,6-O-sulfuryl-alpha-D-mannofuranoside (1). In a Path A, reaction of the 5,6-cyclic sulfate 1 with 2-lithio-1,3-dithiane afforded 2-(methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-mannofuranosid-6-yl)-1,3-dith iane (2). Treatment of 2 with n-butyllithium then alkyl iodide gave the corresponding 2-(methyl 5-O-alkyl-6-deoxy-2,3-O-isopropylidene-alpha-D-mannofuranosid-6-yl )-1,3- dithiane. Reaction of 2 with n-butyllithium and 5,6-cyclic sulfate 1 furnished 2-[methyl 6-deoxy-2,3-O-isopropylidene-5-O-(methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-manno-furanosid-6-yl)-alpha-D - mannofuranosid-6-yl]-1,3-dithiane. 2-(Methyl 6-deoxy-2,3-O-isopropylidene-5-O-methyl-alpha-D-mannofuranosid- 6-yl)-1,3-dithiane was converted into the lithiated anion, which after treatment with alkyl halide afforded the corresponding 2-alkyl-C-(methyl 6-deoxy-2,3-O-isopropylidene-5-O-methyl-alpha-D-mannofuranosid-6-y l)-1,3- dithiane. In a Path B, 5,6-cyclic sulfate 1 reacted with 2-alkyl-2-lithio-1,3-dithiane derivatives, which led after acidic hydrolysis to 2-alkyl-2-(methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-mannofuranosid-6-yl)-1,3-dith iane accompanied by methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-lyxo-hexofuranos-5-u loside as the by-product. This methodology was applied to synthesize 2-(methyl 6-deoxy-2,3-O-isopropylidene-5-O-methyl-alpha-D-mannofuranosid-6-y l)-2- (methyl 6-deoxy-2,3-O-isopropylidene-alpha-D-mannofuranosid-6-yl)-1,3-dith iane.     

2-nitroimidazol-5-ylmethyl as a potential bioreductively activated prodrug system: reductively triggered release of the PARP inhibitor 5-bromoisoquinolinone.

5-Chloromethyl-1-methyl-2-nitroimidazole reacted efficiently with the anion derived from 5-bromoisoquinolin-1-one to give 5-bromo-2-((1-methyl-2-nitroimidazol-5-yl)methyl)isoquinolin -1-one. Biomimetic reduction effected release of the 5-bromoisoquinolin-1-one. The 2-nitroimidazol-5-ylmethyl unit thus has potential for development as a general prodrug system for selective drug delivery to hypoxic tissues.     

Synthesis of glycosides of 3-deoxy-4-thiopentopyranosid-2-uloses and their reduction products: 3-deoxy-4-thiopentopyranosides

Michael addition of common thiols to the enone system of (2S)-2-benzyloxy-2H-pyran-3(6H)-one (1) afforded the corresponding 3-deoxy-4-thiopentopyranosid-2-ulose derivatives (2-4). The reaction was highly diastereoselective, and the addition was governed by the quasiaxially disposed 2-benzyloxy substituent of the starting pyranone. As expected from the enantiomeric excess of 1 (ee > 86%) the corresponding thiouloses 2-4 exhibited the same optical purity. However, the enantiomerically pure thioulose 5 was obtained by reaction of 1 with the chiral thiol, N-(tert-butoxycarbonyl)-L-cysteine methyl ester. The thio derivative 7 was also synthesized by reaction of 6 (enantiomer of 1) with the same chiral thiol. Alternatively, 4-thiopent-2-uloses 9-12 were prepared in high optical purity by 1,4-addition of thiols to (2S)-[(S)-2'-octyloxy]dihydropyranone 8. Similarly, reaction of 13 (enantiomer of 8) with benzenemethanethiol afforded 14 (enantiomer of 10). This way, the stereocontrol exerted by the anomeric center on the starting dihydropyranone led to 4-thiopentuloses of the D and L series. Sodium borohydride reduction of the carbonyl function of uloses 10 and 12 gave the corresponding 3-deoxy-4-thiopentopyranosid-2-uloses (16-19). The diastereomers having the beta-D-threo configuration (16, 18) slightly predominated over the beta-D-erythro (17, 19) analogues. However, the reduction of the enantiomeric pyranones 10 and 14 with K-Selectride was highly diastereofacial selective in favor of the beta-D- and beta-L-threo isomers 16 and 20, respectively.     

Synthesis of non-glycosidic 4,6'-thioether-linked disaccharides as hydrolytically stable glycomimetics

Michael addition of 1,2:3,4-di-O-isopropylidene-6-thio-alpha-D-galactose (2) to 2-propyl 6-O-acetyl-3,4-dideoxy-alpha-D-glycero-hex-3-enopyranosid-2-ulose (1) afforded, as the major diastereoisomer, 2-propyl 6-O-acetyl-3-deoxy-4-S-(6-deoxy-1,2:3,4-di-O-isopropylidene-alpha-D-galactopyranos-6-yl)-4-thio-alpha-D-threo-hexopyranosid-2-ulose (3, 91% yield). Reduction of the carbonyl group of 3, followed by O-deacetylation gave the two epimers 7 (alpha-D-lyxo) and 8 (alpha-D-xylo) in a 1:2 ratio. On removal of the protecting groups of 8 by acid hydrolysis, formation of an 1,6-anhydro bridge was observed in the 3-deoxy-4-thiohexopyranose unit (10). The free non-glycosidic thioether-linked disaccharide 3-deoxy-4-S-(6-deoxy-alpha,beta-D-galactopyranos-6-yl)-4-thio-alpha,beta-D-xylo-hexopyranose (11) was obtained by acetolysis of 10 followed by O-deacetylation. A similar sequence starting from the enone 1 and methyl 2,3,4-tri-O-benzoyl-6-thio-alpha-D-glucopyranoside (12) led successfully to 2-propyl 3-deoxy-4-S-(methyl 6-deoxy-alpha-D-glucopyranos-6-yl)-4-thio-alpha-D-lyxo-hexopyranoside (17) and its alpha-D-xylo analog (19, major product). In this synthetic route, orthogonal sets of protecting groups were employed to preserve the configuration of both reducing ends and to avoid the formation of the 1,6-anhydro ring.     

Study of 1-deoxy-1-(indol-3-yl)-L-sorbose, 1-deoxy-1-(indol-3-yl)-L-tagatose,and their analogs

Alkaline degradation of the ascorbigen 2-C-[(indol-3-yl)methyl]-alpha-L-xylo-hex-3-ulofuranosono-1,4-lactone (1a) led to a mixture of 1-deoxy-1-(indol-3-yl)-L-sorbose (2a) and 1-deoxy-1-(indol-3-yl)-L-tagatose (3a). The mixture of diastereomeric ketoses underwent acetylation and pyranose ring opening under the action of acetic anhydride in pyridine in the presence of 4-dimethylaminopyridine (DMAP) with the formation of a mixture of (E)-2,3,4,5,6-penta-O-acetyl-1-deoxy-1-(indol-3-yl)-L-xylo-hex-1-enitol (4a) and (E)-2,3,4,5,6-penta-O-acetyl-1-deoxy-1-(indol-3-yl)-L-lyxo-hex-1-enitol (5a), which were separated chromatographically. Deacetylation of 4a or 5a afforded cyclised tetrols, tosylation of which in admixture resulted in 1-deoxy-1-(indol-3-yl)-3,5-di-O-tosyl-alpha-L-sorbopyranose (12a) and 1-deoxy-1-(indol-3-yl)-4,5-di-O-tosyl-alpha-L-tagatopyranose (13a). Under alkaline conditions 13a readily formed 2-hydroxy-4-hydroxymethyl-3-(indol-3-yl)cyclopenten-2-one (15a) in 90% yield. Similar transformations were performed for N-methyl- and N-methoxyindole derivatives.     

RNA RECOGNITION BY FLUOR-AROMATIC SUBSTITUTED

RNA exhibits a higher structural diversity than DNA and is an important molecule in the biology of life. It shows a number of secondary structures such as duplexes, hairpin loops, bulges, internal loops, etc. However, in natural RNA, bases are limited to the four predominant structures U, C, A, and G and so the number of compounds that can be used for investigation of parameters of base stacking, base pairing, and hydrogen bond is limited. We synthesized different fluoromodifications of RNA building blocks: 1′-deoxy-1′-phenyl-β-d-ribofuranose (B), 1′-deoxy-1′-(4-fluorophenyl)-β-d-ribofuranose (4 FB), 1′-deoxy-1′-(2,4-difluorophenyl)-β-d-ribofuranose (2,4 DFB), 1′-deoxy-1′-(2,4,5-trifluorophenyl)-β-d-ribofuranose (2,4,5 TFB), 1′-deoxy-1′-(2,4,6-trifluorophenyl)-β-d-ribofuranose, 1′-deoxy-1′-(pentafluorophenyl)-β-d-ribofuranose (PFB), 1′-deoxy-1′-(benzimidazol-1-yl)-β-d-ribofuranose (BI), 1′-deoxy-1′-(4-fluoro-1H-benzimidazol-1-yl)-β-d-ribofuranose (4 FBI), 1′-deoxy-1′-(6-fluoro-1H-benzimidazol-1-yl)-β-d-ribofuranose (6 FBI), 1′-deoxy-1′-(4,6-difluoro-1H-benzimidazol-1-yl)-β-d-ribofuranose (4,6 DFBI), 1′-deoxy-1′-(4-trifluoromethyl-1H-benzimidazol-1-yl)-β-d-ribofuranose (4 TFM), 1′-deoxy-1′-(5-trifluoromethyl-1H-benzimidazol-1-yl)-β-d-ribofuranose (5 TFM), and 1′-deoxy-1′-(6-trifluoromethyl-1H-benzimidazol-1-yl)-β-d-ribofuranose (6 TFM). These amidites were incorporated and tested in a defined A, U-rich RNA sequence (12-mer, 5′-CUU UUC XUU CUU-3′ paired with 3′-GAA AAG YAA GAA-5′). Only one position was modified, marked as X and Y, respectively. UV melting profiles of those oligonucleotides were measured.     

EFFICIENT CHEMO-ENZYMATIC SYNTHESES OF PHARMACEUTICALLY USEFUL UNNATURAL 2′-DEOXYNUCLEOSIDES

Our chemo-enzymatic method was successfully applied to the synthesis of 2-chloro-2′-deoxyadenosine (CdA, cladribine) in two ways: 1) direct conversion of chemically synthesized 2-deoxy-α-D-ribose 1-phosphate (dRP) to CdA; 2) a two-step route via 9-(2-deoxy-β-D-ribos-1-yl)-2,6-dichloropurine (Cl₂Pu-dR, 5).     

Heterocyclization of 3-deoxy-D-erythro-hexos-2-ulose-1,2-bis(thiosemicarbazone). Crystal structure of the major diastereomer

Both thiosemicarbazone groups of the derivative 1 of 3-deoxy-D-erythro-hexos-2-ulose underwent, on acetylation, a heterocyclization process to give (5R,5'R)-2,2'-diacetamido-4,4'-di-N-acetyl-5'-(1-deoxy-2,3,4-tri-O-acetyl-D-erythritol-1-yl)-5,5'-bis(1,3,4-thiadiazoline) (2) as a major product. The X-ray diffraction data of a single crystal of 2 indicated the R,R configuration for the stereocenters of the thiadiazoline rings (C-5 and C-5'). In the solid state, 2 adopts a sickle conformation (by clockwise rotation of the C-2-C-3 axis of the sugar chain) which has a S//O 1,3-parallel interaction. In solution, as determined by (1)H NMR spectroscopy which included NOE experiments, a similar sickle conformation was observed. From the reaction mixture of acetylation of 1 was isolated the bis(thiadiazoline) 3 as a by-product. The configuration of the C-5 and C-5' stereocenters of 3 were respectively assigned as S,R by comparison of the physical and spectroscopic data of this compound with those of 2.     

Stereoselective synthesis and X-ray structure of 1-(4-O-benzyl-1,5-anhydro-2,3-dideoxy-D-arabino-hex-1-enitol-3-yl )-4-me thoxy-1H-pyrimidin-2-one

The intramolecular glycosylation of a 6-O-(4-methoxypyrimidin-2-yl) derivative of phenyl 2,3-didehydrohex-2-eno-1-thiopyranoside afforded 3-deoxy-3-(4-methoxypyrimidin-2-on-1-yl)glycal as the major product in a stereoselective manner. The isolated 3'-deoxyglycal nucleoside was characterized by X-ray and NMR spectral analyses.     

Synthesis of [18F]-labeled EF3 [2-(2-nitroimidazol-1-yl)-N-(3,3,3-trifluoropropyl)-acetamide], a marker for PET detection of hypoxia

[18F]-2-(2-Nitroimidazol-1-yl)-N-(3,3,3-trifluoropropyl)-acetamide ([18F]-EF3) has been prepared, in 65% chemical yield and 5% radiochemical yield, by coupling 2,3,5,6-tetrafluorophenyl 2-(2-nitroimidazol-1-yl) acetate 1 with [18F]-3,3,3-trifluoropropylamine 7. This original radiolabelled key-synthon was obtained in 40% overall chemical yield by oxidative [18F]-fluorodesulfurization of ethyl N-phthalimido-3-aminopropane dithioate 4, followed by deprotection with hydrazine of the resulting [18F]-N-phthalimido-3,3,3-trifluoropropylamine 5. All the process was performed within 90 min, from the [18F]-HF production in the cyclotron to the purification of the final target.     

Purin-6-yl 6-deoxy-1-thio-beta-D-glucopyranoside. Enzymology, chemistry, and cytotoxicity

Purin-6-yl 6-deoxy-1-thio-beta-D-glucopyranoside (4) is a substrate for almond beta-glucosidase and a weak competitive inhibitor of bovine liver beta-D-glucuronidase (Ki approximately 20mM). Both 4 and purine-protonated 4 undergo hydrolysis catalyzed by dilute acid in the pH range 0.17-2.59. These results are compared with those previously obtained with ammonium (purin-6-yl 1-thio-beta-D-glucopyranosid)uronate, (purin-6-yl 1-thio-beta-D-glucopyranosid)uronamide, purin-6-yl 1-thio-beta-D-glucopyranoside, and purin-6-yl 2-deoxy-1-thio-beta-D-glucopyranoside, and it is concluded that the data support an involvement of substituents at C-5 in producing productive Michaelis-complex conformers. The 6-deoxyglucoside is more active than the D-glucosiduronic acid in an L1210 mouse screen.     

Preparation of 2-amino-2-C-glycosyl-acetonitriles from C-glycosyl aldehydes by Strecker reaction

Synthesis of new 2-amino-2-C-d-glycosyl-acetonitriles in a Strecker reaction from various C-glycosyl aldehydes, chiral amines, and HCN was carried out. While aminonitriles from glycal and 2-deoxy-β-d-glycosyl aldehydes were prepared in satisfactory yields, lower yields were obtained with C-glycosyl aldehydes. Strecker reaction with the benzyl-protected 1-C-formyl-d-galactal and S- or R-1-phenylethylamine (S-PEA or R-PEA) yielded predominantly the R-configured C-glycosyl aminoacetonitrile. The direction of the nucleophilic addition appears to be governed by the configuration of the anomeric carbon with β-linked sugars. Since the stereochemistry of the transition state is unknown according to the configuration of the major product a Felkin–Ahn selectivity can be mainly presumed.     

A 2-nitroimidazole carbamate prodrug of 5-amimo-1-(chloromethyl)-3-[(5,6,7-trimethoxyindol-2-yl)carbony l]-1,2-dihydro-3H--benz[E]indole (amino-seco-CBI-TMI) for use with ADEPT and GDEPT.

The synthesis of a 2-nitroimidazol-5-ylmethyl carbamate prodrug 10 of the potent minor groove alkylating agent amino-seco-CBI-TMI 3 is described. Chemical, radiolytic, and enzymic reductions of a model 2-nitroimidazol-5-yl carbamate 8 show release of the amine effector upon reduction. Prodrug 10 gives a ten fold increase in cytotoxicity against human ovarian carcinoma SKOV3 cells in the presence of E. coli B nitroreductase (NTR) and a 21-fold increase in cytotoxicity against a SKOV3 cell line (SC3.2) transfected with the gene for NTR. The cytotoxicity of 10 increased 15- to 40-fold under hypoxia. Prodrug 10 has significant potential as a prodrug for use in ADEPT and GDEPT applications, and as a hypoxia-selective cytotoxin.     

3-(1,2,3-Triazol-1-yl)-1-thio-galactosides as small, efficient, and hydrolytically stable inhibitors of galectin-3

Copper(I)-catalyzed addition of alkynes to methyl 3-azido-3-deoxy-1-thio-beta-D-galactopyranoside afforded stable and structurally simple 3-deoxy-3-(1H-1,2,3-triazol-1-yl)-1-thio-galactosides carrying a panel of substituents at the triazole C4 in high yields. The 3-(1H-[1,2,3]-triazol-1-yl)-1-thio-galactoside collection synthesized contained inhibitors of the tumor- and inflammation-related galectin-3 with Kd values as low as 107 microM, which is as potent as the natural disaccharide inhibitors lactose and N-acetyllactosamine.     

Highly diastereoselective synthesis of enantiopure naphthylaminoalcohols with analgesic properties

The diastereoselective synthesis via Grignard reaction of enantiopure analgesic naphthylaminoalcohols has been performed. The chiral racemic key intermediate 3-dimethylamino-2-methyl-1-(naphthalen-2-yl)propan-1-one and enantiomers were prepared and transformed into the desired compounds by addition of the organometallic reagent. The chemical characterization of all diastereoisomers was accomplished by 1H NMR and HPLC analyses and the absolute configuration assigned by CD spectroscopy. The in vitro and in vivo profile has also been evaluated.     

Novel vasopressin V2 receptor-selective antagonists, pyrrolo[2,1-a]quinoxaline and pyrrolo[2,1-c][1,4]benzodiazepine derivatives.

The intent of the work was to study the structure-activity relationships of AVP receptor antagonists bearing a chiral ring as a partial structure since such studies had been reported for only achiral compounds. In the present paper, we deal with compounds consisting of the chiral tricyclic hetero ring (1,2,3,3a,4,5-hexahydropyrrolo[1,2-a]quinoxaline and 1,2,3,10,11,11a-hexahydro-1H-pyrrolo[2,1-c][1,4]benzodiazepine) and 2-phenylbenzanilide analogues. These compounds exhibited a highly selective affinity for V2 receptor, and their stereochemical configuration had a great influence on V2 receptor binding. VP-343 (N-[4-[[(2S,3aR)-2-hydroxy-2,3,3a,4-tetrahydropyrrolo[1,2-a] quinoxalin-5(1H)-yl]carbonyl]phenyl]-4'-methyl[1,1'-biphenyl]-2-ca rboxamide), VP-365 (N-[4-[[(11aS)-2,3,11,11a-tetrahydro-1H-pyrrolo[2,1-c][1,4]benz odiazepin-10(5H)-yl]carbonyl]phenyl][1,1'-biphenyl-2-carboxamide) and VP-339 (N-[4-[[(11aS)-5-oxo-2,3,11,11a-tetrahydro-1H-pyrrolo[2,1-c][1,4]+ ++benzodiazepin-10(5H)-yl]carbonyl]phenyl][1,1'-biphenyl]-2-carboxami de) were the most potent compounds in vitro and in vivo. The IC50 values of VP-343, VP-365 and VP-339 against V2 receptor were 0.772, 1.18 and 0.216 nM, respectively. The ED300 values (dose required to increase three times the urine volume of the control rats; oral administration) of VP-343, VP-365 and VP-339 were 0.22, 0.31 and 0.78 mg/kg, respectively.     

Difference in transglycosylation between human pancreatic and salivary alpha-amylases

Transglycosylation reactions of alpha-amylases from human pancreatic juice and saliva were examined by using O-6-deoxy-6-[(2-pyridyl)amino]-alpha-D-glucopyranosyl-(1 leads to 4)-O-alpha-D-glucopyranosyl-(1 leads to 4)-O-alpha-D-glucopyranosyl-(1 leads to 4)-O-alpha-D-glucopyranosyl-(1 leads to 4)-D-glucopyranose as a substrate and O-alpha-D-glucopyranosyl-(1 leads to 4)-O-alpha-D-glucopyranosyl-(1 leads to 4)-1-deoxy-1-[(2-pyridyl)amino]-D-glucitol as an acceptor. The transfer reaction was estimated by quantitation of O-alpha-D-glucopyranosyl-(1 leads to 4)-1-deoxy-1-[(2-pyridyl)amino]-D-glucitol produced by the enzymes from the transfer products, because the acceptor was not hydrolyzed. The amount of O-alpha-D-glucopyranosyl-(1 leads to 4)-1-deoxy-1-[(2-pyridyl)amino]-D-glucitol in the digest with pancreatic alpha-amylase was six times that in the digest with salivary alpha-amylase at the stage when the substrate was completely consumed, and the difference increased gradually on further incubation. The phenomenon can be applied to differentiate the two alpha-amylases in human serum.     

A novel synthesis of acyclonucleosides via allylation of 3-[1-(phenylhydrazono)-L-threo-2,3,4-trihydroxybut-1-yl]quinoxalin-2(1H)one

The allylation of 3-[1-(phenylhydrazono)-L-threo-2,3,4-trihydroxybut-1-yl]quinoxalin-2(1H)one (1) gave, in addition to the anticipated 1-N-allyl derivative (2), a dehydrative cyclized product, 1-N-allyl-3-[5-(hydroxymethyl)-1-phenylpyrazol-3-yl]quinoxalin-2-one (4) and its isomeric O-allyl derivative 3. The O-allyl group in 3 underwent acetolysis under acetylation conditions, in addition to the acetylation of the hydroxyl group, to afford 2-acetoxy-3-[5-(acetoxymethyl)-1-phenylpyrazol-3-yl]quinoxaline (8) instead of the O-acetyl derivative of 3. Allylation of the tri-O-acetyl derivative of 1 caused the elimination of a molecule of acetic acid in addition to N-allylation to give 1-N-allyl-3-[3,4-di-O-acetyl-2-deoxy-1-(phenylhydrazono)but-2-en-1-yl]quinoxalin-2-one (11). Hydroxylation of the allyl group gave a glycerol-1-yl acyclonucleoside which can be alternatively obtained by a displacement reaction of the tosyloxy group in 2,3-O-isopropylidene-1-O-(p-tolylsulfonyl)glycerol (14), followed by deisopropylidenation. 1-N-(2,3-Dibromopropyl)-3-[5-(hydroxymethyl)-1-(4-bromophenyl)pyrazol-3-yl]quinoxalin-2-one (15) underwent azidolysis to give a 2,3-diazido derivative. The assigned structures were based on spectral analysis. The activity of compounds 2, 4, 6, and 15 against hepatitis B virus was studied.     

Synthesis and biological activity of novel thiazolidin-4-ones with a carbohydrate moiety

Some novel 2-aryl-3-[5-deoxy-1,2-O-isopropylidene-α-d-xylofuranose-5-C-yl] thiazolidin-4-ones were synthesized by the three-component condensation of an amino sugar 1, an aromatic aldehyde 2, and mercaptoacetic acid 3 in the presence of DCC and DMAP at room temperature. Two diastereoisomers 4 and 5 were afforded as the main products in totally isolated yields of 25.4-70%. The reaction was carried out with almost no observed stereoselectivity except in the case of 2c, which showed a moderate stereoselectivity. The structures of the new compounds were determined by NMR spectroscopy and mass spectrometry (MS), and the configuration of the newly generated chiral carbon (C-2) in the thiazolidin-4-one ring was tentatively assigned based on the X-ray crystallographic structure of 5d and the comparison of their corresponding NMR signals. The antitumor (human cervical cancer cells) activity and the inhibition against the glycosidases (α-glucosidase, β-glucosidase, α-amylase) have been evaluated for the new compounds, some of which exhibited antitumor activity.     

Synthesis of 4-cyano- and 4-nitrophenyl 2,5-anhydro- 1,6-dithio-alpha-D-gluco- and -alpha-L-guloseptanosides carrying different substituents at C-3 and C-4

Treatment of 1,6:2,5-dianhydro-3,4-di-O-methanesulfonyl-1-thio-D-glucitol in methanol with sodium hydroxide afforded 1,6:2,5:3,4-trianhydro-1-thio-allitol, 1,4:2,5-dianhydro-6-methoxy-1-thio-D-galactitol, 1,6:2,5-dianhydro-4-O-methyl-1 -thio-D-glucitol, 1 ,6:2,5-dianhydro-3-O-methanesulfonyl-1 -thio-D-glucitol and 1 ,6:2,5-dianhydro-4-deoxy-1-thio-D-erythro-hex-3-ulose (14) in 5, 4, 28, 5.5 and 41% yield, respectively. Formation of these derivatives can be explained via a common sulfonium intermediate. Reduction of 14 with sodium borohydride and subsequent acetylation afforded 3-O-acetyl-1,6:2,5-dianhydro-4-deoxy-1-thio-D-xylo-hexitol, the absolute configuration of which was proved by X-ray crystallography. The 1,6:2,5-dianhydro-1-thio-D-hexitol derivatives in which the free OH groups were protected by acetylation, methylation or mesylation were converted by a Pummerer reaction of their sulfoxides into the corresponding 1-O-acetyl hexoseptanose derivatives which were used as donors for the glycosidation of 4-cyano- and 4-nitrobenzenethiol, respectively. The Pummerer reaction of 1,6:2,5-dianhydro-4-deoxy-3-O-methyl-1-thio-D-xylo-hexitol S-oxide gave, besides 1-O-acetyl-2,5-anhydro-3-deoxy-4-O-methyl-6-thio-alpha-L- (23) and 1-O-acetyl-2,5-anhydro-4-deoxy-3-O-methyl-6-thio-alpha-D-xylo-hexoseptanose (25), 1-O-acetyl-4-deoxy-2,6-thioanhydro-D-lyxo-hexopyranose, formed in a rearrangement reaction. The same rearrangement took place, when a mixture of 23 and 25 was used as donor in the glycosidation reaction with 4-cyanobenzenethiol, applying trimethylsilyl triflate as promoter. The oral antithrombotic activity of the obtained alpha-thioglycosides was determined in rats, using Pescador's model.