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Russian Chemical Bulletin, International Edition, Vol. 60, No. 5, pp. 1004—1011, May, 2011 1004Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 980—986, May, 2011.1066?5285/11/6005?1004 © 2011 Springer Science+Business Media, Inc.A new synthesis of the 3,6?branched hexasaccharide fragmentof the cell wall mannan in Candida albicans,corresponding to the antigenic factor 4*D. A. Argunov, a A. A. Karelin, b A. A. Grachev, b Yu. E. Tsvetkov, b and N. E. Nifantiev ba Higher Chemical College of the Russian Academy of Sciences,9 Miusskaya pl., 125047 Moscow, Russian Federationb N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences,47 Leninsky prosp., 119991 Moscow, Russian Federation.Fax: +7 (499) 135 8784. E?mail: nen@ioc.ac.ruIn the context of the project dealing with the synthesis and immunological study of theimmunodominant fragments of the cell wall mannan in Candida albicans, the hexamannosidefragment corresponding to the antigenic factor 4 was assembled using the scheme [3+2+1].The yield of the target hexasaccharide with the ( α 1 → 3)?glycosidic bond was higher than thatobtained according to the previously used assembly scheme [2+2+2].Key words: Candida albicans, mannan, oligomannosides, synthesis.The present work is part of the project aimed at thesynthesis and study of immunological properties of oli?gosaccharides corresponding to the mannan fragments ofthe cell wall of the Candida fungi. Dimorphic yeastlikefungi Candida albicans is part of the normal microflora ofskin, mucous membranes, and the gastrointestinal tract.However, immunocompromised people may be vulner?able to superficial and deep candidiases 1 . The Candida cellwall is the first to interact with a host organism and isresponsible for the antigen response, adhesion, and inter?cellular interactions. 2The cell wall mannan 3 is a ( α 1 → 6)?linked chain withside oligomannoside branches attached to its separatemannose residues through ( α 1 → 2)?bonds. These branch?es in turn may contain ( α 1 → 2)?, ( α 1 → 3)?, ( α 1 → 6)?, and( β 1 → 2)?linked mannose residues. It is the side chains thatare responsible for the antigen specificity of Candida. Ear?lier, it has been demonstrated that the carriers of the anti?genic factor 4 are 3,6?branched structures (for example,structures I and II). 4In this communication, we describe a new approach tothe synthesis of 3,6?branched hexamannoside 3?amino?propylglycoside 1. The presence of an amino group in theaglycone allows subsequent covalent bonding to high?mo?lecular?weight carriers and tags of various types.Earlier, 5 we have obtained hexamannoside 1 by suc?cessively joining disaccharide units 4, 5, and 2 accordingto the scheme [2+2+2] (Scheme 1, pathway a). However,glycosylation of tetrasaccharide 3 with disaccharide 2 inthe final step of the assembly of the carbohydrate chain isaccompanied by the formation of a great amount of a by?product containing the ( β 1 → 3)?bond ( α : β = 2 : 1), which* Dedicated to Academician of the Russian Academy of Sciences V. N. Charushin on the occasion of his 60th birthday.III