2-Oxoglutaric Acid → (6,6-Dimethyl-5,6-dihydro-4H-pyrrolo[3,2,1-ij] quinolin-1-yl)Acetic Acid

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Reaction Steps

To a solution of glacial acetic acid (80 mL) and concentrated hydrochloric acid (9 mL) was added 3,4-dihydro-4,4-dimethyl-1-(2H)-quinolinamine (9.5 g, 53.9 mmol) and 2-ketoglutaric acid (9.7 g, 65.1 mmol) and the suspension heated at reflux for 3 hours. After cooling the solvents were removed under reduced pressure and the residue dissolved in 500 mL of ethyl acetate. The ethyl acetate solution was washed with water (3×150 mL) and saturated aqueous sodium chloride (1×50 mL), dried over sodium sulfate, filtered and concentrated under reduced pressure. The residue was subjected to silica gel chromatography, eluting with 1-4% methanol in dichloromethane. Fractions containing product were combined and concentrated under reduced pressure to provide 4.45 g (34%) of the desired compound as a tan foam. An impure fraction was extracted with 1N sodium hydroxice (2×50 mL) and the combined aqueous layers washed with diethyl ether (20 mL) and made acidic with concentrated hydrochloric acid (8 mL). This aqueous mixture was extracted with dichloromethane (2×100 mL), followed by drying (Na2SO4) to provide an additional 2.55 g (19%) of desired product

Provenance & Evidence