Triethylamine → 5'-O-[N-[N-{N-(Nalpha,Nepsilon-dibenzyloxycarbonyllysyl)alanyl}phenylalanyl]isoleucyl]-5-fluorouridine

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Reaction Steps

1.04 Grams (1.65 mmol) of 5'-O-{N-(N-alanylphenylalanyl)isoleucyl}-5-fluorouridine hydrochloride obtained in Example 9 was dissolved in dimethylformamide (10 ml), and 0.815 g (1.97 mmol) of Nα,Nε -di-benzyloxycarbonyllysine and 0.375 g (2.30 mmol) of diethylphosphoryl cyanide were then added. To this solution was added under ice-cooling 0.60 g (5.90 mmol) of triethylamine, and the mixture was stirred for 1 hour at room temperature. The reaction liquid was concentrated under reduced pressure, and the residue was subjected to separation/purification by way of silica gel column chromatography (first time: a linear gradient of chloroform containing 2%→6% methanol; second time: a linear gradient of chloroform containing 3%→6% methanol) whereby 0.85 g (52.3%) of 5'-O-[N-[N-{N-(Nα,Nε -dibenzyloxycarbonyllysyl)alanyl}phenylalanyl]isoleucyl]-5-fluorouridine was obtained as a colorless powdery solid.

Provenance & Evidence