Lithium Hydroxide → [2-[2-(2,4-Difluorophenyl)ethyl]-4-oxopyrido[2,3-d]pyrimidin-1(4H)-yl]acetic acid

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Reaction Steps

Ethyl [2-[2-(2,4-difluorophenyl)ethyl]-4-oxopyrido[2,3-d]pyrimidin-1(4H)-yl]acetate (Int. C1) (32.76 g, 1 equiv) was dissolved in ethanol (350 ml) and water (70 ml), cooled in ice, then aqueous lithium hydroxide (2M solution, 43.42 ml, 0.99 equiv) was added. Stirring was continued for 2 h at room temperature. The solution was concentrated in vacuo and the residue was redissolved in water (700 ml) and saturated aqueous sodium bicarbonate (50 ml), then washed with ethyl acetate (200 ml). The aqueous layer was acidified to pH 2 with 2M hydrochloric acid, and the precipitate was filtered off, washed with ice water (50 ml) and dried in vacuo (50° C., 16 h) to obtain the desired product (23.2 g).

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