Yield:-

Reaction Conditions:

with selenium(IV) oxide in ethyl acetate at 70; for 2 h;diatomaceous earth;

Steps:

31

A mixture of 2,3-dimethylpyrazine (2Og, 18.5mmol), selenium dioxide (41.06g, 37mmol) and diatomeous earth (2Og) in EtOAc (500ml) was stirred and heated at 7O⁰C for 2 hours. The mixture was allowed to cool and the insoluble matter was removed by filtration EPO through diatomeous earth. The filtrate was washed with saturated aqueous sodium hydrogen carbonate solution and then saturated aqueous sodium chloride solution, dried (MgSO₄) and the solvent removed by evaporation. The residue was suspended in water (100ml) and hydroxylamine (45ml of a 50% aqueous solution) was added. The mixture was stirred at ambient temperature for 18 hours and the mixture then extracted with EtOAc. The extracts were combined, washed with saturated aqueous sodium chloride solution, dried (MgSO₄) and the solvent removed by evaporation. The residue was triturated with isohexane to give 3- methylpyrazine-2-carboxaldehyde oxime (9.65g, 38%); NMR Spectrum 2.67 (s, 3H), 8.23 (s, IH), 8.45-8.49 (m, 2H), 11.87 (s, IH).

References:

WO2006/106307,2006,A1 Location in patent:Page/Page column 110-111