Water → rac-Tert-butyl 7,8-dihydroxy-2,3-di-p-tolyl-7,8-dihydropyrido[2,3-b]pyrazine-5(6H)-carboxylate

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Reaction Steps

To a solution of tributylmethylammonium chloride (7.27 g, 30.8 mmol) in DCM (50 ml) was added potassium permanganate (4.87 g, 30.8 mmol) portionwise over 10 minutes at room temperature. On completion the reaction mixture was allowed to stir under an atmosphere of nitrogen for 30 minutes and then cooled down to 0° C. tert-Butyl 2,3-di-p-tolylpyrido[2,3-b]pyrazine-5(6H)-carboxylate (step 1)(7.5 g, 18.14 mmol) in DCM (50 ml) was added dropwise and the mixture was stirred at 4° C. for 10 minutes. To this mixture was added a solution of sodium bisulfite (11.32 g, 109 mmol) in water (50 ml) keeping the temperature below 10° C. The suspension was filtered through coarse Celite® (filter material) and washed through with DCM (200 ml). The organic layer was separated and the aqueous layer washed with DCM (50 ml). The combined organic portions were dried over MgSO4, filtered and evaporated to dryness. The residue was purified by flash chromatography using a 125 g silica column eluting with 0-10% MeOH in DCM. The product fractions were combined and evaporated to dryness. The resulting oil was dissolved in EtOAc (approx. 15 ml). The resulting suspension was diluted with iso-hexane/EtOAc (2:1, 20 ml) and filtered to afford the titled compound as a pale yellow solid;

Provenance & Evidence