2-Methylquinoline-4-carboxylic acids are widely used in organic synthesis for the preparation of various derivatives possessing high biological activity [133]. These compounds are usually obtained by the Pfitzinger reaction, ie, by heating a mixture of 5- substituted isatin with acetone in the presence of alkali. For example, 2-methylquinoline-4- carboxylic acid was synthesized in such a way in 50% yield [335], and 2, 6- ...
