Selective phosphitylation of the primary hydroxyl group in unprotected carbohydrates and nucleosides

[GRAPHICS] Carbohydrates and nucleosides containing a phosphate at the less-hindered p rimary hydroxyl group are often prepared using a protection/deprotection st rategy, Herein we report that the phosphoramidite method can be used to sel ectively incorporate phosphorus at the primary hydroxyl group of O-unprotec ted carbohydrates and nucleosides; in situ oxidation of the resulting phosp hite triester yields the phosphate triester.