Before revision: In one method, a phosphate mono-ester is dissolved in N,N-dimethylformamide (DMF) and activated using triphenylphosphine (PPh3) and 2,2’-Dithiodipyridine (2,2’-DTDP) in the presence of triethylamine (TEA) base and excess imidazole.
After revision: anhydrous pyridine orIn one method, a phosphate mono-ester is dissolved in N,N-dimethylformamide (DMF) and activated using triphenylphosphine (PPh3) and 2,2’-Dithiodipyridine (2,2’-DTDP) in the presence of triethylamine (TEA) base and excess imidazole.