3,4-dihydro-2H-pyran → 2-Acetyl-5-ethyl-7,7-dimethyl-1-(tetrahydro-pyran-2-yl)-5,7-dihydro-1H-imidazo[4,5-f]indol-6-one

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Reaction Steps

2-Acetyl-5-ethyl-7,7-dimethyl-5,7-dihydro-1H-imidazo[4,5-f]indol-6-one (11.7 g, 43.1 mmol) and p-toluenesulfonic acid monohydrate (0.82 g, 4.3 mmol) were dissolved in dichloromethane (200 mL). To this solution 3,4-dihydro-2H-pyrane (4.81 g, 56 mmol) was added and the mixture stirred at reflux for 24 h. The mixture was filtered, the filtrate washed with water (2×100 mL), dried over sodium sulfate and concentrated in vacuo. The crude product was purified by column chromatography on silica (dichloromethane/methanol 93:3) yielding 6.8 g (44%) of a light yellow solid.

Provenance & Evidence