Water → tert-butyl (1S,3R)-3-(2-(5-tosyl-5H-pyrrolo[2,3-b]pyrazin-2-yl)hydrazinecarbonyl)cyclopentylcarbamate

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Reaction Steps

To mixture of 2-hydrazinyl-5-tosyl-5H-pyrrolo[2,3-b]pyrazine (2.50 g, 8.24 mmol, Preparation #9) and (1R,3S)-3-(tert-butoxycarbonylamino)cyclopentanecarboxylic acid (2.08 g, 9.07 mmol, Peptech) in DCM (30 mL) was added EDC.HCl (1.90 g, 9.89 mmol). After about 4.5 h, water (30 mL) was added and the layers were separated. The aqueous layer was then extracted with EtOAc (15 mL). The combined organic layers were washed with brine, dried over anhydrous MgSO4, filtered, and concentrated under reduced pressure. The crude material was dissolved in DCM (15 mL) and purified by silica gel chromatography eluting with a gradient of 40-100% EtOAc in heptane to give tert-butyl (1S,3R)-3-(2-(5-tosyl-5H-pyrrolo[2,3-b]pyrazin-2-yl)hydrazinecarbonyl)cyclopentylcarbamate (4.20 g, 97%): LC/MS (Table 2, Method a) Rt=2.27 min; MS m/z: 515 (M+H)+.

Provenance & Evidence