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Reactivity and crystal structure of 1,2:3,4:5,6-Tri-O-isopropylidene-D-gluconolactone

100%

Jarosz S. , Ciunik Z.

Polish Journal of Chemistry

1998

tom Vol. 72, nr 7

1182-1190

1,2:3,4,5,6-Tri-O-isopropylidene-D-gluconate (1) undergoes the beta-elimination reaction in the presence of LDA to afford 3-deoxy-1,2:5,6-di-O-isopropylidene-D-erythro-hex-3-enolactone (6). Attempts to prepare the phosphonate 4 by reaction of 1 with dimethyl methylphosphonate in the presence of LDA failed; only elimination product 6 was isolated from the reaction mixture. The sugar phosphonate 8 (protected form of 4) was prepared from methyl 2-O-benzyl-3,4:5,6-di-O-isopropylidene gluconate (7) by reaction with (-)CH2P(O)(OMe)2. The crystal structure of 1 is reported.

Removal of Water - a Factor Influencing the Synthesis of Alkynes in a Phase-Transfer Catalyzed - beta - Elimination Reaction

88%

Zakrzewski J. , Huras B. , Sas A. , Żelechowski K. , Bombińska D.

Polish Journal of Chemistry

2008

tom Vol. 82, nr 5

1051-1057

Acetylene derivatives 4 were synthesized from the corresponding vicinal bromo compounds 2 in the phase-transfer catalyzed hydrogen bromide - beta elimination reaction using solid potassium hydroxide as a base, xylene as a solvent, and a phase-transfer catalyst. The yields of the synthesized acetylene derivatives 4 were substantially improved when water formed in the process had been removed.

Subtle differences in glycosylation of blood group M and N type glycophorin A detected with anti-Tn lectins and confirmed by chemical analysis

75%

Krotkiewski H. , Duk M. , Lisowska E.

Acta Biochimica Polonica

1995

tom 42

nr 1

A higher content of Tn and sialyl-Tn receptors in glycophorin A of blood group N than in that of blood group M was suggested by reactions with anti-Tn lectins. Analysis of [^-elimination products of two blood group M and two blood group N preparations by gas liquid chromatography-mass spectrometry showed that GalNAc- -ol was detectable in minor amounts in all analyzed samples and its content was higher in the products obtained from desialylated antigens. Moreover, the content of Gal N Ac- -ol detected in blood group N samples was almost twice as high as in respective blood group M samples. Since blood group M and N antigens differ in two amino-acid residues, our results support the existence of sequence-dependent differences in efficiency of substitution of glycophorin GalNAc-Ser/Thr residues with galactose.

Application of aqueous hydrazine solution for beta-elimination of O-glycans from gastric mucin

75%

Kisiel D. , Gindzienski A. , Gadek A.

Acta Biochimica Polonica

1999

tom 46

nr 3

O-Glycans from pig gastric mucin were released by β-elimination in 0.2 M triethylamine and 50% aqueous hydrazine water solution. The released glycan hydrazides were isolated using Centricon 10 separators, brought to their reducing form and reductive by labelled with p-aminobenzoic acid ethyl ester (ABEE). Labelled products were fractionated into neutral and acid fractions on a Bio-Gel P4 column, calibrated with a mixture of dextran oligosaccharides, labelled according to the same procedure.