Tetrabutylammonium Fluoride → 2-bromo-5H-pyrrolo[2,3-b]pyrazine

Participants

Reaction Steps

A solution of N-(5-bromo-3-((trimethylsilyl)ethynyl)pyrazin-2-yl)acetamide [Intermediate AR] (2.6 g, 8.4 mmol) and tetrabutylammonium fluoride [1 M in THF] (18 mL, 18 mmol) in anhydrous THF (26 mL) was heated at 75° C. for 20 h, after which it was partitioned between EtOAc and H2O. The organic layer was washed with brine, dried over Na2SO4, and evaporated in vacuo to yield a residue that was purified via silica gel chromatography eluting with 30% EtOAc in hexanes to give the title compound as a tan solid (0.69 g, 42%). 1H NMR (CDCl3, 300 MHz): δ 8.88 (bs, 1H), 8.34 (s, 1H), 7.62 (t, J=3.3 Hz, 1H), 6.71 (dd, J=3.6 Hz, 3.9 Hz, 1H). HPLC retention time: 1.73 minutes. MS ESI (m/z): 198.2, 200.2 (M+H)+, calc. 197.

Provenance & Evidence