4-Toluenesulfonyl chloride → 2-Bromo-5-((4-methylphenyl)sulfonyl)-5H-pyrrolo(2,3-b)pyrazine

Participants

Reaction Steps

To a solution of 5-bromo-3-((trimethylsilyl)ethynyl)pyrazin-2-amine (3.00 g, 11.1 mmol, prepared using A from 3,5-dibromopyrazin-2-amine with ethynyltrimethylsilane) in DMF (60 mL) at about 0° C. was added 60 wt % NaH (0.577 g, 14.4 mmol) in three portions. After about 15 min, TsCl (2.75 g, 14.4 mmol) was added and the mixture was allowed to warm slowly to rt. After about 16 h, the mixture was poured into ice-cold water (120 mL) and the precipitate was collected by vacuum filtration. The crude solid was dissolved in DCM (15 mL) and purified by silica gel chromatography eluting with DCM to give 2-bromo-5-tosyl-5H-pyrrolo[2,3-b]pyrazine (2.16 g, 52%): LC/MS (Table 2, Method c) Rt=1.58 min; MS m/z: 352 (M+H)+.

Provenance & Evidence