Sodium Hydroxide → (+/-)-2-[2-(7-Chloro-1,8-naphthyridin-2-yl)-3-oxo-1-isoindolinyl]-6-methyl-3-oxoheptanoic acid

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Reaction Steps

A solution of 23 g of ethyl 2-[2-(7-chloro-1,8-naphthyridin-2-yl)-3-oxo-1-isoindolinyl]-6-methyl-3-oxoheptanoate in 235 cm3 of 98% sulphuric acid is stirred for 20 hours at a temperature of approximately 20° C. and is then poured into 1.5 kg of ice. The precipitate obtained is separated by filtration, washed with water to a pH=6 and dried in air. The solid obtained is taken up in 3.8 liters of distilled water and 480 cm3 of a 0.1N aqueous sodium hydroxide solution. The insoluble product is separated by filtration, the filtrate is acidified to a pH=3 by addition of a 0.1N aqueous hydrochloric acid solution. The precipitate obtained is separated by filtration, washed with distilled water and then with isopropyl ether and dried at 20° C. under reduced pressure (0.07 kPa). 9.2 g of (±)-2-[2-(7-chloro-1,8-naphthyridin-2-yl)-3 -oxo-1-isoindolinyl]-6-methyl-3-oxoheptanoic acid, melting at 176° C., are thus obtained.

Provenance & Evidence