Stereoselective Synthesis of Anomers of 5-Substituted 2′-Deoxyuridines

The substitution reaction of 5-substituted 2,4-bis(trimethylsilyloxy)pyrimidines with 3,5-bis(O-p-chlorobenzoyl)-2-deoxy-α-d-ribofuranosyl chloride was investigated. In the presence of p-nitrophenol, β anomers were formed stereoselectively, whereas the addition of organic bases brought forth stereoselective formation of α anomers. Stereoselectivity of the reaction depends on the substituents at 5-position of disilylpyrimidines, additives, and the concentration of each reagent. The α and β anomers of 5-substituted 2′-deoxy-uridines were synthesized through the deacylation of α and β anomers of 5-substituted 3′,5′-di-O-(p-chlorobenzoyl)-2′-deoxyuridines.