Sulfuric Acid → (7R,8R,9R)-2,3-Dimethyl-8-hydroxy-7-(2-hydroxyethoxy)-9-phenyl-7,8,9,10-tetrahydroimidazo[1,2-h][1,7]naphthyridine

Participants

Reaction Conditions

Reaction Steps

To a suspension of 2.00 g (6.40 mmol) (7R,8R,9R)-7,8-Dihydroxy-2,3-dimethyl-9-phenyl-7.8.9.10-tetrahydroimidazo[1.2-h][1.7]naphthyridine in 2-methoxyethanol (100 ml) is added 1.26 g (12.8 mmol) sulfuric acid and the mixture is stirred for 3 h at 55° C. Subsequently the reaction is poured out into a of 0° C. cooled aqueous solution of sodium hydroxide (2N). The mixture is extracted with dichloromethane two times. The combined organic layer are washed with water four times, dried over sodium sulfate and concentrated in vacuo. The crude product is purified by column chromatography (diethyl ether/2-propanol: 10/1) to give 0.35 g (0.99 mmol/16%) of the title compound as a colourless solid with a melting point of 107–109° C. (diethyl ether).

Provenance & Evidence