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