Ammonium Chloride → (7R,8R,9R)-2,3,7-trimethyl-7,8-dihydroxy-9-phenyl-7,8,9,10-tetrahydroimidazo[1,2-h][1,7]naphthyridine

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Reaction Steps

3.5 g of (8R,9R)-2,3-dimethyl-8-hydroxy-9-phenyl-7,8,9,10-tetrahydroimidazo[1,2-h][1,7]naphthyridin-7-one are suspended in 70 ml of tetrahydrofuran under argon and treated dropwise at −50° C. with a solution of methyllithium (1.6M solution in diethyl ether). The temperature is then allowed to rise to room temperature, and the mixture is poured into a saturated aqueous ammonium chloride solution and extracted three times with 100 ml of dichloromethane each time. The combined organic phases are washed with a little water, dried over sodium sulfate and concentrated to dryness in vacuo. The oily residue obtained is chromatographed on silica gel (eluent: dichloromethane/methanol 13/1). 1.66 g of the title compound are obtained as colorless crystals of melting point 137-8° C. (diethyl ether).

Provenance & Evidence