Hydrazine → 2-Ethyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine

Participants

Reaction Steps

To a solution of 1-chloro-5,7-nonanedione (14.74 g, from Step A) in a mixture of CH3CN (100 mL) and H2O (33 mL) was added 4.87 mL of hydrazine. After refluxing for 18 h, the reaction mixture was partitioned between EtOAc and aqueous NaHCO3 (saturated). Aqueous layer was extracted with EtOAc (3×). Combined organic phase was washed with brine and dried over anhydrous MgSO4. After concentration, the residue was purified by flash chromatography with 20% EtOAc in hexanes followed by 50% EtOAc in hexanes to give the title compound as a viscous oil. 1H NMR (500 MHz, CDCl3) δ 1.24 (t, 3H, J=7.5 Hz), 1.79–1.85 (m, 2H), 1.95–2.05 (m, 2H), 2.62 (q, 2H, J=7.8 Hz), 2.75 (t, 2H, J=6.4 Hz), 4.08 (t, 2H, J=6.1 Hz), 5.78 (s, 1H).

Provenance & Evidence