反应详情

温度

35 °C

Manganese dioxide (150 g) was added to a suspension of ethyl 6-hydroxy-3,5-dimethyl-4,5-dihydropyrazine-2-carboxylate (121 g, 610.44 mmol) in DCM (1.8 L) at ambient temperature giving rise to a 2° C. exotherm. The reaction was stirred for 10 minutes then warmed to 35° C. for 1 hour. The reaction was incomplete so an additional 115 g of Manganese dioxide was added and the reaction stirred for 1 hour at 35° C. then stirred to cool to ambient temperature. The reaction was filtered through a short bed of silica and washed through with 2 L of 1:1 EtOAc/iso-hexane and finally 2×2 L EtOAc. The fractions were then combined and reduce in-vacuo to give an orange solid, which was slurried in 300 mL of 1:1 EtOAc/iso-hexane, filtered and washed with iso-hexane to afford the title compound (87 g, 72.6%) as an orange solid.

1. customgiving rise to a 2° C. exotherm
2. additionwas added
3. stirringthe reaction stirred for 1 hour at 35° C.
4. stirringthen stirred
5. temperatureto cool to ambient temperature
6. filtrationThe reaction was filtered through a short bed of silica
7. washwashed through with 2 L of 1:1 EtOAc/iso-hexane and finally 2×2 L EtOAc
8. customto give an orange solid, which
9. filtrationfiltered
10. washwashed with iso-hexane