6,7,8-Trifluorocarbostyril → 6,7,8-Trifluoro-3,4-dihydrocarbostyril

Participants

Reaction Steps

6,7,8-Trifluorocarbostyril (24.35 g), suspended in a mixture of ethanol (450 cc) and dimethylformamide (150 cc), is hydrogenated with stirring at approximately 50° C. in the presence of Raney nickel (5 g) under a pressure of 1 atmosphere, until the absorption of hydrogen is complete. The Raney nickel used, of W-2 grade, is washed beforehand with 2% aqueous acetic acid solution (50 cc), with water (2×50 cc) and with ethanol (3×50 cc). The reaction mixture is treated with dimethylformamide (250 cc) and filtered at approximately 50° C. through diatomaceous silica. The filtrate is concentrated under reduced pressure (20 kPa) at approximately 70° C. The dry extract is taken up with water (150 cc), drained and washed with water (2×50 cc). 6,7,8-Trifluoro-3,4-dihydrocarbostyril (23.6 g) is obtained in the form of a light beige solid, m.p. 217° C., which is used without further purification for the subsequent steps.

Provenance & Evidence