Azetidine → Azetidin-1-yl(2-methyl-4-nitro-2H-pyrazol-3-yl)methanone

Participants

Reaction Steps

To a suspension of 2-methyl-4-nitro-2H-pyrazole-3-carboxylic acid (300 mg, 1.75 mmol), azetidine (354 μl, 5.25 mmol) and diisopropylethylamine (920 μl, 5.26 mmol) in ethyl acetate (7.5 ml) was added 1-propanephosphonic acid cyclic anhydride (3.68 ml, 6.13 mmol; 50% in ethyl acetate) at 0° C. The ice bath was removed and stirring at r.t. was continued for 40 h. The reaction mixture was poured into ethyl acetate (100 ml) and extracted with sodium bicarbonate (saturated aqueous solution) water and brine. The aqueous layer was back-extracted with ethyl acetate, the combined organic phases were dried, evaporated, and the product was purified by silica gel chromatography using an amine phase and a heptane/ethyl acetate gradient to yield a white solid (269 mg, 73%).

Provenance & Evidence