Branched tetrasaccharide synthesis

To achieve the synthesis of the branched tetrasaccharide 11, a further building block fucosyl donor 12 was chosen, which promised a highly stereoselective glycosylation outcome. By using the benzoyl galactosyl... 

Paulsen, H, Wilkens, R, Brockhausen, I, Building units of oligosaccharides. CIV. Synthesis of branched tetrasaccharide and pentasaccharide structures of A-glycoproteins methylated at 4 -OH of the branching unit, Liebigs Ann. Chem., 1303-1313, 1992. 

H. Paulsen, R. Lebuhn, and O. Lockoff, Building blocks of oligosaccharides. XXXVIII. Synthesis of the branched tetrasaccharide building block of the key sequence of N-gly coproteins, Carbohydr. 

The coupling protocols described in the two previous examples can be combined to allow for the synthesis of branched carbohydrates.19 The automated solid-phase synthesis of a tetrasaccharide is illustrated in Scheme 4. Both glycosyl phosphate and glycosyl imidate building blocks were used along with acetate and levulinate esters as temporary protecting groups. 

C. Berlind and S. Oscarson, Synthesis of a branched heptose- and Kdo-containing common tetrasaccharide core structure of Haemophilus influenzae lipopolysaccharides via a l,6-anhydro-L-g7ycero-/i-D-/Kanno-heptopyranose intermediate, J. Org. Chem., 63 (1998) 7780-7788. 

Plante OJ, Palmacci ER, Seeberger PH. Automated solid-phase synthesis of oligosaccharides. Science. 2001 291 1523-1527. Hewitt MC, Seeberger PH. Automated solid-phase synthesis of a branched Leishmania cap tetrasaccharide. Org. Lett. 2001 2 3699-3702. 

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