R. Rao Koganty

βGal(1–3)GalNAc block donor for the synthesis of TF and α Sialy(2–6)TF as glycopeptide building blocks

Abstract 4,6-Benzylidene protected N-acetylgalactosamine β-glycosylated at the 3-position with peracetylated galactose is found to be an excellent donor for the synthesis of Thomsen-Freidenreich (TF) family of antigens. These may serve further as building blocks for the synthesis of mucin derived glycopeptides and as intermediates for further extention to trisaccharides such as sialyl-TF and 6-O-βGlcNAc-TF(core 2). TF and Sialylated TF are widely regarded as tumor associated and are being investigated as antigens for the immunotherapy of cancers of epithelial origin.

Steric control of N-acetylgalactosamine in glycosidic bond formation

Abstract N-Acetylgalactosamine, protected with a 4,6-cyclic acetal followed by selective acylation at 3-OH, provides an excellent donor for the synthesis of α-glycosides, particularly the cancer associated antigens such as Tn, TF, Sialyl-Tn and Sialyl-TF. This fast and efficient synthesis is easily adaptable for commercial production of mucin type glycopeptides with O-linked carbohydrate structures which are currently being investigated as vaccines against cancers.

Mucin type glycopeptides: Synthesis of Core 2, Core 6 and F1-α building blocks and some unexpected reactions

Abstract Protected Core 2 and 6 and F1-α analogs were synthesized using the 4,6-diol of Tn-Ser/Thr and TF-Ser/Thr. Acetylation of glucosamine in acetic anhydride/pyridine resulted in an additional and unusual N-acetylation at the Fmoc protected amine of serine and threonine followed by β-elimination of the aglycons. Normal glucosamine acetylation was carried out at −20°C for 20 minutes to accomplish in synthesis of Core 2, Core 6 and F1-α as glycopeptide building blocks.

A NOVEL GLYCOSYL DONOR FOR THE SYNTHESIS OF CANCER SPECIFIC CORE 5 AND SIALYL CORE 5 AS GLYCOPEPTIDE BUILDING BLOCKS

Abstract Trichloroacetimidate at 1 and 3 position of 4,6-benzylidenyl N-acetylgalactosamine serves as a leaving group for glycosylation and a selective and acid sensitive protecting group respectively. This versatile donor, while forming exclusive α-glycoside with serine/threonine, serves as a fascile precursor to 3-OH which can be generated in acid medium without affecting 4,6-acetal protecting group or the protecting groups of serine/threonine. Synthesis of cancer associated carbohydrate Core 5 and its sialylated analog are accomplished through the use of this donor.