Acetone → (7R,8R,9R)-8-Hydroxy-7-methoxy-2-methyl-9-phenyl-7,8,9,10-tetrahydroimidazo[1,2-h][1,7]naphthyridine

Participants

Reaction Conditions

Reaction Steps

To a suspension of 0.62 g (2.10 mmol) (7S,8R,9R)-7,8-dihydroxy-2-methyl-9-phenyl-7.8.9.10-tetrahydroimidazo[1.2-h][1.7]naphthyridine in dimethoxypropane is added 0.51 g (26.2 mmol) p-toluenesulphonic acid and acetone (4.0 ml). The mixture is stirred for 6 h at 60° C. and 96 h at 25° C. The reaction is quenched by adding of saturated aqueous sodium hydrogen carbonate solution. Subsequently the mixture is extracted twice with dichloromethane. The combined organic layers are washed with brine, dried over sodium sulphate and evaporated in vacuo. The crude product is purified by column chromatography (dichloromethane/methanol: 100/3) to give 0.12 g (0.34 mmol/16%) of the title compound as an amorphous solid. 1H-NMR (200 MHz, [D6] DMSO): δ=2.29 (s, 3H), 3.25 (s, 3 H), 4.05 (q, 1H), 4.32 (d, 1H), 4.47 (dd, 1H), 6.61 (d, 1H), 7.19–7.46 (m, 5H), 7.54 (s, 1H), 7.72 (d, 1 H).

Provenance & Evidence