2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → (9S)-2,3-Dimethyl-9-phenyl-7,8,9,10-tetrahydroimidazo[1,2-h][1,7]naphthyridin-7-one

Participants

Reaction Steps

63.5 g (0.22 mol) of (9S)-2,3-dimethyl-9-phenyl-5,6,7,8,9,10-hexahydroimidazo[1,2-h][1,7]naphthyridin-7-one are dissolved in 250 ml of toluene and 250 ml of tetrahydrofuran, and cooled to 0° C. 59 g (0.26 mol) of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone are introduced in portions of 10 g over a period of 1 h with mechanical stirring. The reaction mixture is stirred at room temperature for 16 h. 1.2 l of 0.5 N sodium hydroxide solution and 1 l of ethyl acetate are then added dropwise. The organic phase is removed and washed with water. The aqueous phase is reextracted with ethyl acetate, and the combined organic phases are dried over sodium sulphate and evaporated. The residue is crystallized at 0° C. in 300 ml of methanol. The solid is filtered off with suction, washed with cold methanol and dried. 20 g (32%) of the title compound are isolated as a pale yellow solid (m.p. 103-105° C.).

Provenance & Evidence