Stanisław Porwański

A polymer-supported ‘one-pot’ phosphine imide reaction on cyclodextrins

Abstract The present work describes the first example of a polymer-assisted ‘one-pot’ phosphine imide reaction using a polymer-bounded triphenylphosphine. The syntheses were performed from the 6-monoazido-β-peracetylated cyclodextrin or from the heptakis-(6-deoxy-6-azido)-β-cyclodextrin and lead to, monosubstituted, polysubstituted or dimer of β-cyclodextrin in good yields (64–43%). The repeatability of the reaction and the polymer regeneration step were investigated.

New synthetic approach to per-O-acetyl-isocyanates, isothiocyanates and thioureas in the disaccharide and cyclodextrin series

An efficient method for the preparation of per-O-acetyl disaccharides and cyclodextrin isocyanates or isothiocyanates by the phosphine imide strategy is reported. Successful one-pot, high yield syntheses of cellobiose, lactose and sucrose isocyanates or/and isothiocyanates pure β-anomers have been completed starting from their corresponding monoazido-per-O-acetyl derivatives. Transformation of the ACEtris-6-azido-per-O-methylated and the ACEtris-6-azido-per-O-acetylated-α-cyclodextrins or of the 6A-azido-6A-deoxy-per-O-acetyl-β-cyclodextrin into the corresponding isocyanates and/or isothiocyanates is also presented. Finally the conversion of the cyclodextrin isothiocyanates by nucleophilic addition of primary and secondary amines into a large panel of original thioureido-cyclodextrins derivatives is described.

An Easy and Efficient Access to Bis-Allyloxy-Arenes

Abstract Bis-allyloxy-arenes were prepared in very good yields by reaction of the bis-hydroxy-arene on the appropriate allyl carbonate at room temperature in the presence of a palladium(O) catalyst.

Synthesis of bis-cellobiose and bis-glucose derivatives of azacrown macrocycles as hosts in complexes with acetylsalicylic acid and 4-acetamidophenol

Two new C2 symmetric bis-cellobiose and bis-glucose azacrown derivatives were prepared according to the one-step procedure using azacrown ethers and azidosaccharides. Their complexes with aspirin and paracetamol were studied with the use of proton NMR spectroscopy. It was found that these pseudocryptands bind aspirin and paracetamol but each one in a different manner.

New sugar-derived bifunctional chiral ureas as highly effective organocatalysts in asymmetric aza-Henry reaction

A simple synthesis of series of new catalysts derived from chiral bifunctional ureas is described. The aza-Henry reaction of imines with nitromethane was promoted by sugar derived bifunctional organocatalysts to give optically active β-nitroamines. The aza-Henry reaction products were obtained in good yields (35-98%) and ee up to 99%.

PALLADIUM(0)-CATALYZED ACCESS TO BIS-GLYCOSYLOXY-ARENES

Bis-glycosyloxy-arenes were prepared in very good yields by reaction of the bis-hydroxy-arene on the appropriate unsaturated glycosyl carbonate at room temperature in the presence of a palladium(0) catalyst.

Synthesis of new saccharide azacrown cryptands

New cryptands including bis-azacrown and saccharidic moieties in their structure were prepared in several steps by applying Staudinger-aza-Wittig reaction (SAW). Syntheses have been started from cheap, easily available commercial compounds such as D-glucose, D-cellobiose and D-lactose subsequently transformed into their derivatives in fairly good yields (60-65%) and suitable to give desired final cryptands by direct SAW coupling reactions.

Palladium-catalyzed synthesis of bis-glycosides of but-2-ene-1,4-diol, butane-1,4-diol, and 1,2-bis(propenyl)benzene

Palladium(0)-catalyzed reaction of various carbohydrates derived from glucofuranose, mannofuranose, ribofuranose, glucopyranose, and glucosamine, bearing a free hydroxyl group, with 1,4-bis-(methoxycarbonyloxy)but-2-ene afforded the corresponding bis-glycosides of butene-1,4-diol. Hydrogenation in the presence of palladium on charcoal of these unsaturated compounds led to the formation of the bis-glycosides of butane-1,4-diol. The condensation was successfully extended to the bis-carbonate of 1,2-bis-[(1-hydroxy)propen-2-yl]benzene and derivatives of glucofuranose, ribofuranose and glucosamine.

Deeper insight into the properties of the newly synthesized macrocycles as drug receptors – some preliminary quantum chemical studies

The article presents the results of our more extended studies performed on one of the carbohydrate derivatives of azacrown ethers that were recently synthesized in our laboratory. An attempt is made to explain the interactions between 1,10-N,N′-bis-(β-D-ureidocellobiosyl)-4,7,13-trioxa-1,10-diazacyclopentadecane (host) and the aspirin molecule using theoretical methods. The structure and other properties of the complex formed by the two molecules revealed by NMR, IR spectrometry and microanalysis are compared to the results of quantum calculations performed with the semiempirical and density functional methods for several selected geometries.

Palladium(0)-catalysed synthesis of 2,3- and 3,4-unsaturated aryl β-O-glycosides

Arylation of 6-O-tert-butyldiphenylsilyl-3,4-di-O-isobutyloxycarbonyl-d-glucal (3) with various phenols in the presence of a catalytic amount of palladium(0) gave the corresponding 2,3- and 3,4-unsaturated β-O-glycosides. The reaction is stereospecific, in all cases, only the β-anomer is formed.