2-Cyanoethyl tetraisopropylphosphorodiamidite → (2R,3R)-1-(Bis(4-methoxyphenyl)(phenyl)methoxy)-2-((4-acetamido-2-oxo-pyrimidin-1(2H)-yl)methyl)butan-3-yl 2-cyanoethyl N,N-diisopropylphosphoramidite

Participants

Reaction Steps

To a stirred solution of 22 (1.0 g, 1.79 mmol) in 25 ml of anhydrous dichloromethane was added diisopropylammonium tetrazolide (0.35 g) followed by 0.8 g (2.66 mmol) of 2-cyanoethyl N,N,N′,N′-tetraisopropylphosphordiamidite. After being stirred at room temperature for 20 hrs the reaction was concentrated, and the residue portioned between ethyl acetate and saturated NaHCO3. The organic phase was washed with saturated NaCl, dried over Na2SO4 and concentrated in vacuo. The crude phosphoramidite was precipitated twice by re-dissolving in small (˜10 ml) amount of ethyl acetate, diluting with hexane (100 ml), allowing precipitate as an oil and decanting the liquid. Drying in vacuo afforded 1.2 g (88%) of 23 as an amorphous white solid. 31P NMR (DMSO-d6): δ 148.03, 147.19.

Provenance & Evidence