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) was refluxed for 3 hours. The reaction mixture was cooled and then was poured into ice/water (3-4 L). A solid formed which was collected by filtration and washed with water. The filtrate was extracted with CH2Cl2 (1 L) and the CH2Cl2 layer was evaporated to about 50 ml and both this solution and the previously isolated solid were purified by column 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