Lithium hydroxide, monohydrate → 7-(7-Ethyl-2,3-di-p-tolyl-7,8-dihydropyrido[2,3-b]pyrazin-5(6H)-yl)heptanoic acid

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Reaction Steps

A (0° C.) cooled solution of ethyl 7-(7-ethyl-2,3-di-p-tolyl-7,8-dihydropyrido[2,3-b]pyrazin-5(6H)-yl)heptanoate (0.22 g, 0.44 mmol) in THF:H2O (4:1, 5 ml) was treated with LiOH.H2O (0.072 g, 1.76 mmol) and stirred at RT overnight. A further 2 equivalents of LiOH.H2O was added and the reaction mixture was heated to 50° C. for 4 hours. The solvent was removed under reduced pressure and the aqueous layer was acidified to pH 3 and partitioned between water and ethyl acetate. The organic layer was washed with saturated brine solution, dried over anhydrous sodium sulphate and concentrated under vacuum. The crude material was purified by chromatography on silica eluting with 10% EtOAc in hexane followed by preparative HPLC (MeCN in water eluent) to afford the titled compound;

Provenance & Evidence