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

Participants

Reaction Steps

24.35 g of 6,7,8-trifluorocarbostyril in suspension in a mixture of 450 cm3 of ethanol and 150 cm3 of dimethylformamide are hydrogenated with stirring, at about 50° C., in the presence of 5 g of Raney nickel under a pressure of 1 atmosphere until the absorption of hydrogen has ceased. The W-2 grade Raney nickel used is washed beforehand with 50 cm3 of an aqueous 2% acetic acid solution, twice 50 cm3 of water and 3 times 50 cm3 of ethanol. 250 cm3 of dimethylformamide are added to the reaction mixture and the mixture is filtered at about 50° C. through diatomaceous silica. The filtrate is concentrated under reduced pressure (20 kpa) at about 70° C. The dry extract is taken up in 150 cm3 of water, drained and washed with twice 50 cm3 of water. 23.6 g of 6,7,8-trifluoro-3,4-dihydrocarbostyril are obtained in the form of a light beige solid melting at 217° C., which is used for the subsequent steps without further purification.

Provenance & Evidence