To a solution of tributylmethylammonium chloride (0.970 g, 4.11 mmol) in DCM (15 ml) at RT under nitrogen was added potassium permanganate (0.650 g, 4.11 mmol) portionwise over 10 minutes. The mixture was cooled to 0° C. and treated dropwise with a solution of tert-butyl 2,3-dip-tolylpyrido[2,3-b]pyrazine-5(6H)-carboxylate (step 2) (1 g, 2.418 mmol) in DCM (10 ml). A solution of sodium bisulfite (1.510 g, 14.51 mmol) in water (12.5 ml) was added keeping the temperature <10° C. The mixture was filtered through Celite® (filter material), washing with DCM. The phases were separated and the organic portion was washed with brine, dried (sodium sulphate), filtered and the solvent was removed in vacuo. The crude product was dissolved in DCM and purified by chromatography on silica eluting with 30-50% EtOAc in iso-hexanes to afford the title compound;
