Aluminium lithium hydride → 1-(1-Methyl-3-pyrrolidinyl)-1H-pyrazol-4-amine

Participants

Reaction Steps

A reaction flask containing a suspension of LAH (499 mg, 13.2 mmol) in THF (22 mL) was evacuated and back-filled with nitrogen three times. A solution of tert-butyl 3-(4-amino-1H-pyrazol-1-yl)pyrrolidine-1-carboxylate (830 mg, 3.3 mmol) in THF (11 mL) was added dropwise, via an addition funnel and the reaction mixture was stirred at rt under nitrogen overnight. The reaction was quenched sequentially with water (1 mL), 1N NaOH (1 mL), and water (3 mL) to afford a suspension. The precipitate was filtered off and washed with ethyl acetate. The combined filtrates were diluted with a small amount of water and transferred to a separatory funnel. The layers were separated, and the aqueous layer was extracted with ethyl acetate. The organics were combined and concentrated to give crude material (137 mg). To recover product in the aqueous layer, the aqueous extraces were lyophilized to give a solid residue. This was suspended in EtOAc and filtered. The filtrate was evaporated to give additional crude material (287 mg). The combined crude was purified via Biotage flash chromatography (25S column, eluting with 7 N NH3/MeOH in DCM (1%-4%)) to give the title compound (279 mg, 51% yield). m/z (APCI+) for C8H14N4 167.2 (M+H)+. 1H NMR (400 MHz, DMSO-d6) δ ppm 1.89-2.00 (m, 1H) 2.20-2.31 (m, 1H) 2.26 (s, 3H) 2.42 (td, J=8.40, 6.19 Hz, 1H) 2.60 (dd, J=9.60, 4.80 Hz, 1H) 2.64-2.77 (m, 2H) 3.79 (br. s., 2H) 4.67 (m, J=9.44, 7.23, 4.67, 4.67 Hz, 1H) 6.87 (s, 1H) 7.07 (s, 1H).

Provenance & Evidence