Phosphorylation disaccharide synthesis

Compound 6-Pre closely resembles the intermediates used by Kusumoto jet al. ([this volume) and by van Boeckel et al. (16) for the preparation of disaccharide oxazolines, which were then elaborated into fully phosphorylated analogs (1,4 -diphosphates). In a formal sense, therefore, the synthesis of 6-Pw effectively constitutes a synthesis, by our revised route, or the 1,4 -bisphosphate having palmitoyl groups at positions 2, 3, 2, and 6. An additional palmitoyl group could be attached at position 4 if desired. 

M. K. Christensen, M. Meldal, K. Bock, H. Cordes, S. Mouritsen, H. Eisner. Synthesis of glycosylated peptide templates containing 6 -0- phosphorylaled mannose disaccharides and their binding to the mannose-6-phosphate receptor. J. Chem. Soc., Perkin Trans. 1 1994, 1299-1310. 

Subsequently, 22a was converted into the per-benzylated glycosyl donor 22b by sequential deacetylation and benzylation under standard conditions in 87 % yield. Glycosylation of acceptor 23 with 22b was performed in the presence of TMSOTf yielding the disaccharide 24 in 80 % yield with complete 1,2-cis stereoselectivity. Ferrieres and Plusquellec described the synthesis of per-acetylated thiopyrimidinyl furanosides and their application to anomeric phosphorylation 32, 33). 

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