| 摘要 |
<p>1-Ethyl 6-fluoro 7-(1-piperazinyl) 1,4-dihydro 4-oxo quinoline carboxylic acid of formula (I) is made by (a) brominating cpd. (II) in 3-position in acid medium to give cpd. (III); (b) treating this with ethyl bromide in basic medium and DMF to give 3-bromo 6-fluoro 7-chloro 1-ethyl 1,4-dihydro 4-oxo quinoline; (c) treating this with CuCN in DMF and then with NaCN to give 1-ethyl 6-fluoro 7-chloro 1,4-dihydro 4-oxo quinoline 3-carbonitrile; (d) treating this in sulphuric/acetic acid medium to hydrolyse the CN gp. and then with NH4OH and active carbon to give 1-ethyl 6-fluoro 7-chloro 1,4-dihydro 4-oxo quinoline 3-carboxylic acid; and (e) substituting the chlorine atom by piperazine, using pyridine or tert. amines, to obtain (I).</p> |
