Diisopropylethylamine → 2-({4-[(2-Chloro-4-nitrophenyl)diazenyl]phenyl}ethylamino)ethyl (2S,4R)-2-{[bis(4-Methoxyphenyl)phenylmethoxy]methyl}-4-{[bis(methylethyl)amino](2-cyanoethoxy)phosphinooxy}pyrrolidinecarboxylate

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Reaction Steps

To a solution of 4a (12.63 g, 15.91 mmol) dissolved in 440 ml of anhydrous methylene chloride, containing 8.0 ml of N,N-diisopropylethylamine, was added 5.94 ml of 2-cyanoethyl diisopropylchlorophosphoramidite. The solution was stirred 30 min under argon at room temperature. The reaction mixture was treated with 10 ml of methanol and poured into 400 ml of 5% sodium bicarbonate solution. The organic phase was dried over sodium sulfate and evaporated. The residue was purified by silica gel chromatography eluting with a gradient of 40-20% hexane in ethyl acetate (2% triethylamine). The pure product fractions were evaporated affording an amorphous solid: 14.75 g (93% yield). 31P NMR (DMSO-d6) δ 146.93 (singlet). Anal. Calcd for C52H61ClN7O9+1.0 H2O: C, 61.68; H, 6.27; N, 9.68. Found: C, 61.44; H, 6.47; N, 9.35.

Provenance & Evidence