Bromine → 3-Bromo-2-ethyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine

Participants

Reaction Conditions

Reaction Steps

To a solution of 2-ethyl-4,5,6,7-tetrahydropyrazolo[1,5-a]pyridine (4.12 g, from Step B) in EtOH (25 mL) was added Br2 (1.42 mL) dropwise at 0° C. The reaction was stirred at 0° C. for 20 min. 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 10% EtOAc in hexanes followed by 20% EtOAc in hexanes to give the title compound as a viscous oil. 1H NMR (500 MHz, CDCl3) δ 1.25 (t, 3H, J=7.5 Hz), 1.80–1.90 (m, 2H), 1.95–2.05 (m, 2H), 2.55–2.70 (m, 4H), 4.07 (t, 2H, J=6.0 Hz).

Provenance & Evidence