| abstract |
A process for the preparation of a 1,8-bridged 4-quinolone-3-carboxylic acid of the formula <IMAGE> comprising in a first reaction step reacting an enamine of the formula <IMAGE> (II) in an anhydrous, aprotic solvent with one equivalent of a base, at a temperature form 80 DEG C. to 180 DEG C., to give a 4-quinolone-3-carboxylic acid derivative of the formula <IMAGE> and, in a second reaction step, reacting that with another equivalent of a base, to give the 1,8-bridged 4-quinolone-3-carboxylic acid derivative of the formula (I) and optionally converting the group Y into a carboxyl group or salt thereof. Both steps may be effected simultaneously in a one-pot process without intermediate isolation of the compound II. Some of the compounds are new. The old and new compounds are antibacterials and promote animal growth. |