Diethyl Oxalate → Pyrido(2,3-b)pyrazine-2,3-diol

Temperature

120 °C

A stirred suspension of 2,3-diaminopyridine (75 g, 687 mmol) in diethyl oxalate (291 ml, 2131 mmol) under N2 was heated to 120° C. After 1 h, the ethanol was distilled off the reaction mixture and the temperature was elevated to 160° C. for a further 2 hours. The reaction mixture was allowed to cool to RT and diluted with diethyl ether (200 ml). The resulting suspension was stirred for 1 hour and the solid was isolated by filtration and dried in a vacuum oven. The solid was suspended in ethanol (500 ml) and sonicated for 1 hour. The suspension was filtered and dried (vacuum oven overnight) to afford the title compound;

1. distillationthe ethanol was distilled off the reaction mixture
2. waitthe temperature was elevated to 160° C. for a further 2 hours
3. temperatureto cool to RT
4. additiondiluted with diethyl ether (200 ml)
5. customthe solid was isolated by filtration
6. customdried in a vacuum oven
7. customsonicated for 1 hour
8. filtrationThe suspension was filtered
9. customdried (vacuum oven overnight)

ORD record

ord-cddfbf3a7dfb47a0941119af4b3ec299

Source dataset

uspto-grants-2015_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09132127B2