1,1'-Carbonyldiimidazole → HCID 68675744, compound

Participants

Reaction Steps

A mixture of 15.3 g of NaH (60% suspension in mineral oil) and 80.0 g of 3-bromo-5-phenyl-pyrazin-2-ol (J Het. Chem., 665 (1978)) was stirred together for 15 min. After gas evolution ceased, 90.0 g of trifluoromethanesulfonic anhydride was added dropwise over one h. The mixture was stirred an additional 30 min. and was filtered through a pad of silica gel and the solids were washed with methylene chloride. Concentration of the filtrate provided 3-bromo-5-phenyl-pyrazin-2-trifluoromethansulfonate that was dissolved in IPA (200 mL) and stirred as 4.48 g of hydrazine was added. The mixture was stirred at ambient temperature for 16 h. The resulting solid was collected, washed with methylene chloride, and dried under reduced pressure. The filtrate was re-subjected to the above reaction conditions a second and third time to provide (3-bromo-5-phenyl-pyrazin-2-yl)-hydrazine as the trifluoromethane sulfonate salt. A solution of 265 mg of (3-bromo-5-phenyl-pyrazin-2-yl)-hydrazine trifluoromethane sulfonate in THF (5.0 mL) was stirred as 243 mg of CDI was added in portions over 15 min. The resulting solution was stirred for 1.5 h and was diluted with EtOAc and washed with water. The organic layer was dried over magnesium sulfate, filtered, and concentrated to provide 8-bromo-6-phenyl-2H-[1,2,4]triazolo[4,3-a]pyrazin-3-one as a tan solid. MS (M+H−)=290.2.

Provenance & Evidence