Methods of producing phosphitylated compounds

Provided are methods of producing phosphitylated compounds, including 3'-O-phosphoramidites, comprising the step of reacting a hydroxyl-containing compound with a phosphitylating agent in the presence of a phosphitylation activator selected from the group consisting of: (1) acid-base complexes derived from an amine base of Formula I wherein R, R1, and R2 are independently C1-C10 alkyl, C3-C10 cycloalkyl, C6-C10 aryl, C7-C10 aralkyl, C1-C10 heteroalkyl, or C1-C10 heteroaryl, wherein any two adjacent R, R1, and R2 may be connected to form a heterocyclic ring; (2) acid-base complexes derived from a diazabicyclo amine base; and (3) combinations of two or more thereof.