Verfahren zur Herstellung von niederen Alkylestern der 6,7-di-Alkoxy-4-hydroxy-3-chinolincarbonsaeure

The invention comprises methyl and ethyl 6,7 - di - isobutoxy - 4 - hydroxy - quinolates and 6,7 - disubstituted - 4 - hydroxy - 3 - quinoline-carboxylic esters of the general formula where R and R1 are alkyl or alkenyl containing 2 to 4 carbon atoms, R2 is alkyl containing up to 4 carbon atoms or allyl, and X is hydroxy when at least one of R and R1 is alkenyl, or when R2 is allyl, or is acetoxy, and the preparation thereof when X is hydroxy by reducing the required 1,2-dialkoxy- or dialkenyloxy-4-nitro-benzene, treating the resultant amino compound with diethylethoxymethylene- or dimethylmethoxymethylene malonate and effecting ring closure by heating at a temperature of 200/250 DEG C. the resulting compound either in a high-boiling solvent or in the presence of phosphorus oxyhalide and in the latter case hydrolysing the resulting 4-halo compound and, when required, preparing C3 or C4 esters (alkyl or allyl) by saponifying the compound thus obtained and subjecting the acid formed to the Fisher-Speier or Schotten-Baumann reaction, or by a transesterification technique. The compounds of the formula wherein X is acetoxy are prepared by acetylating the corresponding free hydroxy compounds. Therapeutic compositions useful in treating coccidially infected chickens and which contain as the active ingredient from 0.006 to 0.1% of a compound of the general formula above in admixture with an edible carrier. 3,4 - Diisobutoxynitrobenzene and 3,4 - bis-(2-methylallyloxy) - nitrobenzene are prepared by reacting catechol with isobutyl bromide and methallyl chloride respectively and nitrating the resulting 1,2 - diisobutoxybenzene and o-bis-(2-methylallyloxy)-benzene. 6,7 - Diisobutoxy - 4 - hydroxy - 3 - quinoline-carbonyl chloride is prepared by reacting 6,7-diisobutoxy - 4 - hydroxy - 3 - quinoline - carboxylate with sodium hydroxide and reacting the resulting 6,7 - diisobutoxy - 4 - hydroxy - quinoline - carboxylic - acid hydrate with SOCl2.