Lewis X pentasaccharide

Cao, S, Gan, Z, Roy, R, Active-latent glycosylation strategy toward Lewis X pentasaccharide in a form suitable for neoglycoconjugate syntheses, Carbohydr. Res., 318, 75-81, 1999. 

Scheme 11.2-1 Retrosynthesis of the building blocks 4-8. Bn - benzyl, protected Lewis X pentasaccharide 1, Lewis Bu - butyl, Fmoc - 9-fluorenylmethoxy-hexasaccharide 2, and Le -Le 1 carbonyl, Lev - levulinoyl, Piv - pivaloyl,...

Cleavage of the ester linker from the resin using a solution of sodium methanolate over a period of 6 h provided the crude oligosaccharides. HPLC purification produced the fully protected Lewis X pentasaccharide 1, Lewis Y hexasaccharide 2, and Ley-Lex nonasaccharide 3 in 12.6, 9.9, and 6.5% yields, respectively [13]. 

Jain, R. K. Matta, K. L., Chemical synthesis of a hexasaccharide comprising the Lewis(x) determinant linked beta-(l->6) to a linear trimannosyl core and the precursor pentasaccharide lacking fucose. Carbohydr. Res. 1996,282, 101-111. 

The thiophenyl Lewis X trisaccharide 92 is now condensed without any problem with the easily available alcohol 93 to give the pentasaccharide 94, as shown in Scheme 27. De-O-benzoylation of 94 gave the triol 95. 

---