Publications by authors named "B S Komarova"

O-Protected oxacarbenium ions are key intermediates of glycosylation reactions. The knowledge of their conformational preferences is crucial for choosing the correct blocking group pattern to achieve the required stereochemical outcome. This article describes a computational study of several glucosyl oxacarbenium cations.

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This study focuses on the synthesis of a series of oligo--(1→6)-D-galactopyranosides bearing -D-galactofuranosyl residues at O-2 and/or O-3, which relate structurally to fragments of glucuronoxylomannogalactan (GXMGal) from the fungal pathogen that causes severe diseases in immunocompromised patients. The preparation of target compounds is based on the use of a selectively O-protected N-phenyltrifluoroacetimidoyl galactopyranoside donor with an allyl group at O-2, levulinoyl group (Lev) at O-3, pentafluorobenzoyl (PFB) group at O-4, and fluorenylmethoxycarbonyl (Fmoc) group at O-6. The choice of protecting groups for this donor ensures the stereospecific formation of (1→6)-glycosidic bonds due to the stereodirecting effect of acyls at O-3, O-4, and O-6.

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Stereospecific α-glucosylation of primary and secondary OH-group at carbohydrate acceptors is achieved using glucosyl -phenyl-trifluoroacetimidate (PTFAI) donor protected with an electron-withdrawing 2,4,5-trifluorobenzoyl (TFB) group at O-6 and the participating levulinoyl (Lev) group at O-3. New factors have been revealed that might explain α-stereoselectivity in the case of TFB and pentafluorobenzoyl (PFB) groups at O-6. They are of conformational nature and confirmed by DFT calculations.

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The polysaccharide mannan is the main surface antigen of the cell wall of fungi, playing an important role in the pathogenesis of diseases caused by these mycopathogens. Mannan has a complex, comb-like structure and includes a variety of structural units, with their combination varying depending on the species and strain. Glucomannan, a polysaccharide from , contains terminal -d-glucose residues attached to oligomannoside side chains.

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