493 



Quinolines 



Oxidative decarboxylation would then yield an inter- 

 mediate of the type isolated, and a one-stage reduction the 

 4-oxyquinolines. The N-oxides might be formed later by 

 post-oxidation. Quinolines are known to be quite suscep- 

 tible to N-oxidation by peroxides or oxygen. 



The structure of the mold product, viridicatin, has been 

 verified by synthesis, while that of cyclopenin is still un- 

 certain. It would appear that these substances are also 

 derivatives of anthranilic acid. In this case, condensa- 

 tion probably occurs with an earlier member of the shiki- 

 mic acid pathway, perhaps prephenic acid or phenyl- 

 pyruvic acid: 



H2C 



COOH c=0 



-CO2 



NH, 



Anthranilic 

 Acid 



c 



O OH 



CH 



y \ 



/ c=o 



\ 



// 



OH 



Phenylpyruvic 

 Acid 



Viridicatin 



Such condensations have been suggested to explain the 

 origin of certain oxyquinoUne plant alkaloids. - 



There is, of course, a possibility for 4-oxyquinoLine for- 

 mation by way of tryptophan and kynurenine : 



O 



C 



\ 

 CH. 



1 

 NH2 CH— NH2 



transamination, 

 dehydration 



COOH 



COOH 



Kynurenine 



This seems to be an unnecessarily indirect route, but all 

 of the schemes shown here await experimental test. 



Ernest Wenkert, Experientia 15 165 (1959). 



