Synthesis
Step 1: Preparation of (2,5-dimethyl-2H-pyrazol-3-yl) methanol (14): to a solution of compound 13 (4.5 g, 24.7 mmol) in THF (60 mL) was added lithium aluminum hydride (LiAlH4) (1.22 g, 32.1 mmol) in batches at 0°C under nitrogen atmosphere. The reaction mixture was stirred at the same temperature for 2-3 h. The excess LiAlH4 was subsequently quenched by addition of saturated sodium sulfate solution.The reaction mixture was filtered and the residue was washed with ethyl acetate. The filtrates were combined and concentrated under reduced pressure to afford the target product (2,5-dimethyl-2H-pyrazol-3-yl) methanol (14) 3 g as a brown solid. Yield: 86%; 1H NMR (200 MHz, CDCl3): δ 6.0 (s, 1H), 4.57 (d, J = 5.9 Hz, 2H), 3.8 (s, 3H), 3.16 (s, 1H), 2.24 (s, 3H); Mass Spectrometry (CI method, isobutane): 127 (M+1, 100%); IR (KBr, cm-1 ): ν max 3281.
