Tetrabutylammonium Fluoride → tert-butyl 4-ethynyl-1H-pyrazole-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

tert-Butyl 4-((trimethylsilyl)ethynyl)-1H-pyrazole-1-carboxylate (3) (3.88 g 14.69 mmole) was dissolved in THF (40 mL) and cooled to 0-5° C. A 1M solution of tetra-n-butylammonium fluoride in THF (16 mL, 16 mmole) was added and the reaction was stirred for 20 minutes. The THF was evaporated and the residue was taken up in ethyl acetate (50 mL) and washed with water (×2) and with brine, then dried and evaporated. The residue was purified on a flash column (silica, eluting with 15% ethyl acetate in cyclohexane) to give the title compound (1.765 g, 62%). 1H-NMR (CDCl3, 500 MHz): δ 1.68 (s, 9H, 3.11 (s, 1H), 7.79 (s, 1H), 8.24 (s, 1H).

Provenance & Evidence