Hydrazine hydrate (1:1) → 5-(3-Pyridyl)-2-pyrazoline

Beteiligte Stoffe

Reaktionsschritte

Under N2 atmosphere, hydrazine hydrate (3.65 mL, 2 equiv.) was added to a solution of 3-(3-pyridyl)acrolein (5.0 g) in t-BuOH (25 mL). The mixture was refluxed for 3 days, followed by evaporation under reduced pressure. The residue was taken up in DCM and washed with 5% aqueous NaHCO3. The organic phase was dried over Na2SO4 and evaporated under reduced pressure. This gave 5.0 g of a red oil, containing 74% of the anticipated product and 26% of the hydrazone intermediate that failed to undergo ring-closure. This material was used in subsequent steps without further purification. Characteristic pyrazoline signals in 1H NMR (400 MHz, CDCl3): δ 2.63-2.75 (m, 1H), 3.13-3.25 (m, 1H), 4.72-4.82 (m, 1H), 6.85 (br s, 1H).

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