IMPROVED METHOD FOR SYNTHESIZING 2'-O-SUBSTITUTED PYRIMIDINE NUCLEOSIDE AND ITS OLIGOMER COMPOUND

摘要

PROBLEM TO BE SOLVED: To provide an improved method for synthesizing a 2-O-substituted pyrimidine nucleoside and an oligomer compound having the nucleoside. SOLUTION: This method comprises a step for reacting 2,2'-anhydropyrimidine nucleoside or 2S,2'-anhydropyrimidine nucleoside represented by the formula (1) [R2 and R3 are each independently H or a protective group of a hydroxy group; X1 is O or S; and R5 and R6 are each independently H or a (substituted) hydrocarbyl] with a weak nucleophilic reagent, e.g. an alcohol in the presence of a Lewis acid to alkylate the compound.