8i 



Tetronic Acids and Other Lactones and Lactams 



don product of a C^r, fatty acid and pyruvate while the latter 

 seems to be the condensation product of a Ck, fatty acid with 

 oxaloacetate. Many other such apparent biosynthetic origins 

 can be detected. 



The biosynthesis of penicillic acid has been studied.- At first 

 glance this would appear to be derived from acetate and 

 dimethylpyruvate, ^-methylglutaconate or a similar unit. It 

 was found that 2-C''*-mevalonic acid lactone was not incorporated 

 into the penicillic acid molecule when added to the growth me- 

 dium of Penicillium cyclophim Westling. However, CH;^C'^OOH 

 was incorporated with equal labeling at the sites shown: 



HO 



CH3O— C 

 CH3 



=CH 



CH3 



CH2 



X 



C— C 



c=o 



o o 



H 



CHo 



/ 



C— C— C=CH— COOH 



OCH3 



Penicillic Acid 



With a relationship to the terpene biosynthetic route ruled out 

 and a similarity to the valine biogenetic pathway also unlikely, 

 the authors suggested a precursor of the orsellinic acid type, 

 perhaps the 4-methyl ether :t 



CH3 



COOH 



OH 



- A. J. Birch, G. E. Blance and Herchel Smith, J. Chem. Soc, 4582 

 (1958). 



t See addendum. 



