Hydrochloric Acid → 2-Hydrazinyl-5-tosyl-5H-pyrrolo[2,3-b]pyrazine

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Reaction Conditions

Reaction Steps

HCl (4 M in 1,4-dioxane, 226 mL, 902 mmol) was added to a mixture of tert-butyl 2-(5-tosyl-5H-pyrrolo[2,3-b]pyrazin-2-yl)hydrazinecarboxylate and tert-butyl 1-(5-tosyl-5H-pyrrolo[2,3-b]pyrazin-2-yl)hydrazinecarboxylate (49.2 g, 122 mmol) in 1,4-dioxane (290 mL). The reaction was heated at about 60° C. for about 2.5 h and then cooled to about 15-20° C. The solid was collected by vacuum filtration, washed with EtOAc (3×50 mL), and then triturated with Et2O (60 mL), collected by vacuum filtration and dried to a constant weight under vacuum to yield 35.6 g of crude solid. The solid was stirred with a mixture of saturated aqueous NaHCO3 and EtOAc (1:1, 400 mL). After about 1 h, the solid was collected by vacuum filtration, washed with ice cold water (3×30 mL) and EtOAc (3×30 mL), and dried in a vacuum oven to a constant weight to afford 2-hydrazinyl-5-tosyl-5H-pyrrolo[2,3-b]pyrazine as a tan solid (21.2 g, 57%): LC/MS (Table 1, Method a) Rt=1.88 min; MS m/z: 304 (M+H)+.

Provenance & Evidence