A mixture of 3,3-dimethyl-2-butanone (6.19 mL) and bis(dimethylamino)methoxymethane (6.61 g) was heated to reflux for 10 hours. Upon completion of the reaction, the reaction mixture was concentrated under reduced pressure. To the concentrated residue was added hydrazine monohydrate (1.60 g) and n-butanol (24.9 mL) and the mixture was heated at reflux for 7 hours. The reaction mixture was again concentrated under reduced pressure to afford 3-tert-butyl-1H-pyrazole (3.79 g, 61% yield) as a yellow oily product. The H-NMR (CDCl3) data of the product were as follows: δ 1.34 (9H, s), 6.10 (1H, d, J = 2.0 Hz), 7.49 (1H, d, J = 2.0 Hz), 10.3 (1H, br s).
