Iodine → 3-Iodo-1,4,5,6-tetrahydrocyclopenta[C]pyrazole

Participants

Reaction Conditions

Reaction Steps

To a mixture of 1,4,5,6-tetrahydrocyclopenta[c]pyrazole-3-carboxylic acid (0.5 g, 3.29 mmol), and sodium bicarbonate (911 mg, 422 μL, 10.8 mmol) in dichloroethane (5 mL) and water (5 mL) were added in one portion sodium iodide (1.28 g, 8.54 mmol) and iodine (1.08 g, 4.27 mmol) and the mixture heated at to 100° C. (oil bath temperature) with vigorous stirring for 24 h. After cooling to 25° C. the mixture was diluted with dichloromethane then washed with 10% Na2S2O3 and saturated NaHCO3. The organic phases were combined, dried (MgSO4) and concentrated to a yellow solid which was dissolved in dichloromethane, cyclohexane added to promote solid formation and allowed to stand. The solid was separated by filtration and dried to give 3-iodo-1,4,5,6-tetrahydrocyclopenta[c]pyrazole (580 mg, 2.48 mmol, 75%) as needles. MS (M+H)+=234.9; 1H NMR (CDCl3) δ: 2.71-2.99 (m, 31H), 2.39-2.66 (m, 4H).

Provenance & Evidence