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

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Reaction Steps

3 g (0.0155 mol) of 5,6-dihydro-4H-imidazo[1,5,4-de]quinoxalin-2(1H)-one in 60 ml of phosphoryl chloride are heated at the reflux temperature for 3 hours. The solvent is evaporated to dryness and the residue taken up successively in ice-cold water and in a concentrated aqueous ammonia solution. Extraction is then carried out twice with ether and the organic phases are combined, dried and evaporated to dryness. The residue is purified by chromatography on a column of silica gel, the eluent being ether. There are obtained 1.8 g of product in the oil form which is used as is in the following stage.

Provenance & Evidence