Chlorosuccinimide → 3-(1-tert-Butyloxycarbonyl-trans-4-(2-pyridyl)-pyrrolidin-3-ylamino)-6-chloro-1-ethoxycarbonylmethylpyrazinone

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Reaction Steps

A stirred solution of 3-(1-tert-butyloxycarbonyl-trans-4-(2-pyridyl)-pyrrolidin-3-ylamino)-1-ethoxycarbonylmethylpyrazinone from step 8 above (2.0 g, 4.5 mmol) and N-chlorosuccinimide (0.67 g, 5.0 mmol) in CHCl3 was heated to reflux for 6 h. More N-chlorosuccinimide (0.20 g, 1.5 mmol) was added and refluxing was continued for 12 h. The reaction was diluted with CHCl3 and washed with aqueous NaHCO3. The organic phase was separated, dried over Mg SO4, filtered, and concentrated in vacuo. The residue was purified by flash column chromatography using a gradient elution of 25-50% EtOAc:hexanes to give the title compound as an amorphous solid (1.5 g, TLC Rf=0.5, 1:1 EtOAc:hexanes; HPLC RT=7.17 min, method A).

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