Tetrabutylammonium Fluoride → tert-butyl 5-ethynyl-3-(pyridin-4-yl)-1H-indazole-1-carboxylate

Participants

Reaction Steps

To a solution of tert-butyl 3-(pyridin-4-yl)-5-((triisopropylsilyl)ethynyl)-1H-indazole-1-carboxylate (3.10 g, 6.5 mmol) in THF (100 ml) was added 1M TBAF in THF (7.2 ml, 7.2 mmol). The reaction was stirred for 3 h at room temperature. Upon completion, the reaction mixture was quenched with the addition of saturated aqueous NH4Cl (50 ml) and extracted with Et2O (3×100 ml). The combined organic extracts were washed with saturated aqueous NaCl (100 ml) and dried with anhydrous Na2SO4. The organic phase was concentrated under reduced pressure and column purified (20-80% EtAOc/Hexane) to give the desired product of tert-butyl 5-ethynyl-3-(pyridin-4-yl)-1H-indazole-1-carboxylate (0.77 g) and the de-Boc product of 5-ethynyl-3-(pyridin-4-yl)-1H-indazole (0.40 g).

Provenance & Evidence