Bicarbonate Ion → 1-[(2,3-Dichlorophenyl)carbonyl]-5-(ethyloxy)-1,2,3,6-tetrahydropyrazine

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Reaction Steps

To a suspension of 4-[(2,3-dichlorophenyl)carbonyl]-2-piperazinone (1 g, 3.66 mmol, e.g. prepared as described in Intermediate 3) in dry Dichloromethane (DCM) (9.15 ml) was added triethyloxonium tetrafluoroborate (1.739 g, 9.15 mmol). The suspension turned shortly to a yellow solution and it was stirred at room temperature under argon. After 5 minutes the mixture was diluted with Dichloromethane (20 mL) and treated with ice (15 mL). The pH was adjusted to circa 7 with saturated bicarbonate solution, the phases were separated and the aqueous extracted with Dichloromethane (50 mL). The combined organics were washed with brine and dried over MgSO4. Evaporation gave 1-[(2,3-dichlorophenyl)carbonyl]-5-(ethyloxy)-1,2,3,6-tetrahydropyrazine (0.98 g) as an orange oil which was used without further purification.

Provenance & Evidence