Реакция #70549

Уравнение реакции

ethyl 3-amino-pyrazole-4-carboxylate

diiodomethane

Isoamyl nitrite

→

title compound

ethyl 3-iodo-1H-pyrazole-4-carboxylate

Условия реакции

Обработка

1. 1
   Температураto warm up to ambient temperature
2. 2
   ТемператураAfter cooling to room temperature
3. 3
   Концентрированиеthe mixture was concentrated
4. 4
   workup.DISSOLUTIONthe residue was dissolved in ethyl acetate (200 mL)
5. 5
   Промывкаwashed with 0.5 M aqueous sodium metasulfite solution (2×70 mL), 1 N HCl and brine
6. 6
   СушкаThe organic solution was dried with magnesium sulfate
7. 7
   Концентрированиеconcentrated
8. 8
   ДругоеThe crude product was purified on a silica gel column
9. 9
   Промывкаeluting with 15% ethyl acetate in hexane

Методика

A mixture of ethyl 3-amino-pyrazole-4-carboxylate (6.4 g, 40 mmole) and diiodomethane (200 g) was cooled to −10° C. Isoamyl nitrite (24 mL, 180 mmole) was added via a syringe over 30 minutes. The mixture was allowed to warm up to ambient temperature and then stirred at 100° C. for 2 hours. After cooling to room temperature, the mixture was concentrated and the residue was dissolved in ethyl acetate (200 mL) and washed with 0.5 M aqueous sodium metasulfite solution (2×70 mL), 1 N HCl and brine. The organic solution was dried with magnesium sulfate and concentrated. The crude product was purified on a silica gel column eluting with 15% ethyl acetate in hexane to provide the title compound. MS (DCI) m/e 266.9 (M+H)+, 283.9 (M+NH4)+.

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