Quinoline 4- carboxylic acids, Pfitzinger synthesis

Quinoline-4-carboxylic acid, 3-hydroxy-Pfitzinger synthesis, 2, 446 Quinoline-4-carboxylic acid, 2-methyl-synthesis, 2, 475... 

Friedlander synthesis, 2, 444 as antipyretic, 1, 172 Quinoline-4-carboxylic acids amination, 2, 236 Beyer synthesis, 2, 475 Pfitzinger synthesis, 2, 446... 

The Pfitzinger reaction entails the synthesis of quinoline-4-carboxylic acids 2 via condensation of isatic acids formed from isatins 1 and a-methylene carbonyl compounds in the presence of strong aqueous bases. Subsequent decarboxylation can afford the corresponding quinolines. " ... 

Carboxylic acids with labile a-methylene protons react with isatin in the presence of strong aqueous base. In the total synthesis of methoxatin, the coenzyme of methanol dehydrogenase and glucose dehydrogenase, Weinreb employs a Pfitzinger condensation of an isatin 37 and pyruvic acid as a key step to provide the 4-quinolinic acid 38 in 50% yield under the standard basic conditions. ... 

The Pfitzinger reaction of isatins with a-methylene carbonyl compounds is widely used for the synthesis of substituted quinoline-4-carboxylic acids. Ivachtchenko and colleagues have recently reported on the Pfitzinger reaction in a series of 5-sulfa-moylisatins (Scheme 6.239) [422]. Treatment of 5-sulfamoylisatins with diethyl mal-... 

PFITZINGER Quinoline synthesis Qumoline-4-carboxylic acids from isatin and o-methylene carbonyl compounds. 

Two related reactions of quinoline construction, the Pfitzinger and Niementowski reaction, can be considered as extensions of the Friedlander synthesis. Niementowski reaction uses anthranilic acid for the synthesis of 4-hydroxy quinolines, and Pfitzinger reaction applies substituted isatins as precursors for ort/io-aminophenylglyoxylic acid, which is used as the condensation component with carbonyl compounds to produce 4-carboxylic acid quinolines. 

Potassium hydroxide Quinoline-4-carboxylic acids from isatins Pfitzinger-Borsdie synthesis... 

---