Phosphorus oxychloride → 2-Chloro-5,6-dihydro-4H-imidazo[4,5,1-ij]quinoline

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Reaction Steps

7.6 g (0.0436 mol) of 5,6-dihydro-4H-imidazo[4,5,1-ij]quino1-2(1H)-one are heated in the presence of 70 ml of phosphoryl chloride at the reflux 20 temperature for 3 hours. The solvent is evaporated to dryness and the residue is taken up in ice. The pH of the reaction mixture is adjusted to 8 with a concentrated sodium hydroxide solution and extraction is carried out with dichloromethane. The organic phase is dried over sodium sulphate and the solvent evaporated to dryness. The residue is purified by chromatography on a column of silica gel, the eluent being an ethyl acetate/hexane (30/70) mixture. There are obtained 5.8 g of product which is used as is in the following stage.

Provenance & Evidence