Synthesis and Use of Glycosyl Phosphites: An Effective Route to Glycosyl Phosphates, Sugar Nucleotides, and Glycosides

An efficient and convenient synthetic route to glycosyl phosphites and phosphates has been developed that uses dibenzyl N.N-diethylphosphoramidite as a phosphitylating reagent. Glycosyl phosphites and phosphates of 2-acetamido-2-deoxy-D-galactose (GalNAc) (29), 2-acetamido-2-deoxy-D-glucose (GlcNAc) (30), D-galactose (Gal) (31), D-glucose (Glc) (32), D-mannose (Man) (33), L-rhamnose (Rha) (34), L-fucose (Fuc) (35), and N-acetylneuraminic acid (NeuAc) (41) were prepared by this procedure. Compounds 29 and 30 were obtained as α anomers exclusively, whereas compounds 31, 32, and 41 were obtained as β anomers, and compounds 33 and 34, as α anomers, predominately. The phosphates are useful for the synthesis of sugar nucleotides, and the phosphites are effective glycosylation reagents.