Hydrazine hydrate (1:1) → 5-(But-3-enyl)-4-phenyl-3-p-tolyl-1H-pyrazole

Participants

Reaction Steps

2-Phenyl-1-p-tolylethanone (1.0 g, 4.76 mmol) was dissolved in Toluene (20 mL). The reaction was cooled in an ice bath and then LiHMDS (4.76 mL, 4.76 mmol) was added slowly via syringe. The reaction was stirred at this temperature for 5 min and then pent-4-enoyl chloride (0.564 g, 4.76 mmol) was added. The reaction was warmed to room temperature and stirred at this temperature for 20 min. After this time EtOH (10 mL), AcOH (2 mL), and hydrazine hydrate (0.231 mL, 4.76 mmol) were added to the reaction. The reaction was heated to 80° C. and stirred at this temperature for an hour. After this time, the reaction was cooled and extracted (50 mL each of EtOAc and 1M NaOH). The aqueous layer was extracted again with EtOAc (50 mL). The combined organic layer was dried, concentrated, and the residue was purified by silica gel column chromatography to give the title compound (355 mg) as a colorless oil. LCMS m/z=289.0 [M+H]+; 1H NMR (400 MHz, DMSO-d6) δ ppm 2.22-2.32 (m, 5H), 2.55-2.69 (m, 2H), 4.86-5.02 (m, 2H), 5.75 (s, 1H), 6.99-7.24 (m, 6H), 7.25-7.31 (m, 1H), 7.33-7.39 (m, 2H), 12.74 (s, 1H).

Provenance & Evidence