Synthesis of inositol glycan cyclic phosphates

摘要

An efficient synthesis of tri-, tetra-, and pentasaccharide cyclic phosphates 1-5, structurally related to natural inositol phosphate glycans, is reported. The title compounds were assembled by PhSeOTf-promoted glycosylation of the known glucosamine precursor, t-butyldimethylsilyl 2-azido-3,6-di-O-benzyl-2-deoxy-#beta#-D-glucopyranoside (8) with protected 1-mehylthio mono-, di-, and trimannosides 7a-c, and, after conversion into glycosyl fluorides, Cp_2ZrCl_2-AgOTf-promoted glycosylation of differentially protected optically pure 1D-myo-inositol 11. The syntheses were completed by installing the cyclic phosphate moieties with methylpyridinium dichlorophosphate and finally, removal of all protecting groups by dissolving-metal reduction.