Sulfuric Acid → 6-[1-(2-Fluorobenzyl)-1H-pyrazolo[3,4-b]pyridin-3-yl]-2-methylpyrido[2,3-b]pyrazin-3(4H)-one

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Reaction Steps

146 mg (0.435 mmol) of the compound from example 43A were initially charged in ethanol (8 ml), then 56 mg (0.48 mmol) of ethyl 2-oxopropanoate were added and the reaction mixture was heated to reflux overnight. Thereafter, a catalytic amount of conc. sulfuric acid was added and the mixture was again heated to reflux overnight. Subsequently, the mixture was cooled to RT, and the solid formed was filtered off, washed with ethanol and dried under high vacuum. The crude product was dissolved in DMSO and separated by means of preparative HPLC (eluent: acetonitrile-water with 0.1% formic acid gradient), and the product fractions were concentrated. This gave 30 mg (18% of theory) of the title compound in solid form.

Provenance & Evidence