Rezsö Bognár

A synthesis of l-ristosamine and a derivative of its C-4 epimer

Abstract A synthesis of l -ristosamine from l -rhamnal is described, involving the sequence of reactions: methoxymercuration, tosylation, azide displacement, and reduction, which gave methyl α- l -ristosaminide (10) . Acid hydrolysis then afforded l -ristosamine hydrochloride. Trifluoroacetylation of the hydrochloride of 10 followed by saponification and oxidation with ruthenium tetraoxide gave methyl 2,3,6-tri-deoxy-3-trifluoroacetamido-α- l - erythro -hexopyranosid-4-ulose (17). Borohydride reduction of 17 gave a separable, 1:1 mixture of methyl 2,3,6-trideoxy-3-trifluoroacetamido-α- l - ribo - and α- l - xylo -hexopyranoside.

Synthesis of D-ristosamine and its derivatives

Abstract A convenient preparative route involving eleven steps starting from D -glucose is described for the synthesis of D -ristosamine ( 15 ) hydrochloride. Methyl 2-deoxy-β- D - arabino -hexopyranoside, prepared from 3,4,6-tri- O -acetyl-1,5-anhydro-2-deoxy- D - arabino -hex- 1-enitol, was benzylidenated, and the product mesylated to give methyl 4,6- O -benzylidene-2-deoxy-3- O -methylsulfonyl-β- D - arabino -hexopyranoside. Azidolysis of this compound and subsequent opening of the 1,3-dioxane ring with N -bromosuccinimide gave methyl 3-azido-4- O -benzoyl-6-bromo-2,3,6-trideoxy-β D - ribo -hexopyranoside. Simultaneous reduction of the azido and bromo groups gave a mixture that was benzoylated to give methyl N,O -dibenzoyl-β- D -ristosaminide and then hydrolyzed to 15 hydrochloride (3-amino-2,3,6-trideoxy- D - ribo -hexopyranose hydrochloride).

Carbocyclic Ring Closure of an Aminodeoxy HEX-5-Enopyranoside

Abstract Ferriers intramolecular carbocyclic ring closure reaction of methyl 3,4-di-O-acetyl-2-benzoyl-amino-2,6-dideoxy-α-O-xylo-hex-5-enopyranoside (2) led to 2L-2,4,513-2,3-di-O-acetyl-4-benzoylamino-5-hydroxy-cyclohexanone (4). Upon acetylation compound 4 underwent B-elimination to give the conjugated enone 5. The convenient preparation of these highly functionalized aminocyclohexanones offers an efficient route to monoamino- or 1,4-diaminocyclitol-type aminoglycoside antibiotic aglycones, starting from 2-amino-2-deoxy-O-glucose.

Heterocyclic compounds from sugars : Part VI. the conformations of 2-(polyhydroxyalkyl)- and 2-(polyacetoxyalkyl)benzothiazoles. A nuclear magnetic resonance study

Abstract The conformation of several 2-(polyhydroxyalkyl)- and 2-(polyacetoxyalkyl)-benzothiazoles has been studied by n.m.r. spectroscopy at 100 MHz in dimethyl sulfoxide- d 6 and chloroform- d solutions, respectively. Compounds having the d - arabino , d - galacto , and d - manno configuration adopt an extended planar conformation in both series. On the other hand, coupling constant data for the d - xylo , d - ribo , and d - gluco configuration indicate that, in these cases, a bent conformation is preferred in which the unfavorable 1,3-dipolar interaction is relieved through rotation at either the C-1-C-2 or C-3-C-4 bond.

Cycloaddition reactions leading to carbohydrate derivatives part I. Hetero diels-alder reaction of monosaccharide O-thioformates

Abstract Monosaccharide O-thioformates under thermal or high-pressure conditions react with various dienes to give O-thiopyran-2-yl saccharides

Synthesis of monosaccharides by oxidation of furfural derivatives

Abstract dl -Ribose, dl -arabinose, and dl -xylose have been synthesized from 2-furaldehyde. Condensation of 2-furaldehyde with pinacol followed by oxidation of the product with bromine water or lead tetra-acetate and reduction with sodium borohydride gave dl -2-(1,4-dihydroxy- cis -but-2-enyl)-4,4,5,5-tetramethyl-1,3-dioxolane ( 4a ). Hydroxylation of the dibenzoate of 4a followed by debenzoylation and hydrolysis gave dl -ribose and dl -arabinose. Epoxidation of 4a with monoperoxysuccinic acid followed by hydrolysis gave dl -xylose.

Stereoselective hydrogenation of methyl dideoxy- and trideoxy-β-D-hex-5-enopyranosides

Abstract Hydrogenation, severally, of methyl 3-azido-2,3,6-trideoxy-β- D - erythro -hex-5-enopyranoside, its 3-benzamido analogue, and methyl 2,6-dideoxy-β- D - threo -hex-5-enopyranoside in the presence of palladium-on-barium sulphate gave the corresponding 6-deoxy-β- D -hexopyranoside derivatives. Stereoselective addition of hydrogen was observed in each case. Methyl 2,6-dideoxy-β- D - arabino -hexopyranoside was also prepared by reductive dehalogenation of methyl 3,4-di- O -benzoyl-6-bromo-2,6-dideoxy-β- D - arabino -hexopyranoside.

SYNTHESIS OF 2-DEOXYALDONONITRILES BY CHAIN ELONGATION OF MONOSACCHARIDE DIETHYL DITHIOACETALS

Die Dithioacetale verschiedener peracetylierter Aldosen (I) werden mit in situ aus Quecksilbercyanid und Iod gebildetem Iodcyan in das Epimerengemisch der Verbindungen (II) umgewandelt.

Modification of acute and chronic liver damage by thiazolidine compounds

As high sulfhydril levels were shown to reduce the action of agents causing tissue-injury, increasing glutathion concentrations may have cytoprotective potential. In this study the hepatoprotective effects of several derivatives of 4-carboxy-5,5-dimethyl thiazolidine, a modulator of glutathion metabolism were studied in rat liver damaged with CC14. It was found that 4(S) carboxy 5,5-dimethyl-2 (5′-nitro-2-furyl) thiazolidine (dimethyl-thiazolidine-nitrofuran: DTNF) had the most significant hepatoprotective action; therefore it was subjected to detailed investigation in various models for acute and chronic liver injury. This compound was shown to ameliorate allylalcohol induced liver injury in rats, galactosamine induced hepatitis of mice and CC14 induced chronic liver damage in rats. Our study on protein synthesis in primary hepatocyte suspension culture showed that cell injury induced by CCI4 could be reduced in the presence of this thiazolidine compound.

DEOXYGENATION OF SULFOXIDES WITH BORON SULFIDE

Abstract Among the reagents used for reducing sulfoxides to sulfides there are a number of sulfur-containing compounds /sulfite, mercaptans, carbodithioic acid, mono- and dithiophosphoric acids, sulfinyl chlorides, thionyl chloride, phosphorus pentasulfide/.