Triphenylphosphine → tert-butyl-3-(3-methyl-4-nitro-1H-pyrazol-1-yl)pyrrolidine-1-carboxylate

Participants

Reaction Steps

To a solution of 3-methyl-4-nitro-1H-pyrazole (3.0 g, 23.6 mmol, 1.00 eq), tert-butyl-3-hydroxypyrrolidine-1-carboxylate (4.42 g, 23.6 mmol, 1.00 eq), and triphenylphosphine (6.19 g, 23.6 mmol, 1.00 eq) in THF (60 mL) was added a solution of diethyl azodicarboxylate (4.34 mL, 23.6 mmol, 1.00 eq) in THF (10 mL) in a drop-wise manner over 30 min. The reaction mixture was allowed to stir at ambient temperature for 20 hr and then concentrated. The crude reaction mixture was purified via repeated flash chromatography on silica gel eluting with a gradient of 0-35% EtOAc in heptane to give the title compound (2.48 g, 35% yield) as a colorless oil that was the early eluting of two structural isomers. 1H NMR (400 MHz, CDCl3) δ ppm 8.15 (s, 1 H) 4.80 (quin, J=5.7 Hz, 1 H) 3.83 (dd, J=6.0, 12.0 Hz, 1 H) 3.79-3.45 (m, 3 H) 2.52 (s, 3 H) 2.38 (q, J=7.0 Hz, 2 H) 1.46 (s, 9 H). m/z (APCI+) for C13H21N4O4 197.2 (M+H)+.

Provenance & Evidence