Phosphorus oxychloride → 1-ethyl-4-chloro-1H-pyrazolo[3,4-b]quinoline

Participants

Reaction Steps

A mixture of N-(1-ethylpyrazol-5-yl)anthranilic acid (278 g, 1.2 mol) and POCl3 (550 g, 3.6 mol) is refluxed for 3 hours. The reaction mixture is cooled and then poured into ice/water (3-4 L). A solid forms which is collected by filtration and washed with water. The filtrate is extracted with CH2Cl2 (1 L) and the CH2Cl2 layer is evaporated to about 50 ml, and both this solution and the previously isolated solid are purified by colunm chromatography on silica gel eluting with CH2Cl2 to afford 190 g (68%) of 1-ethyl-4-chloro-1H-pyrazolo[3,4-b]quinoline.

Provenance & Evidence