10 FATTY ACID METABOLISM IN MICROORGANISMS 



son with lactobacillic acid, four long-chain fatty acids con- 

 taining the cyclopropane ring— namely, racemic cis and 

 trans 9,10-methyleneoctadecanoic acids and racemic cis and 

 trans 1 1,12-methyleneoctadecanoic acids— were synthesized. 

 The synthetic route to the trans series is illustrated on Fig. 

 1.6. 



Trrtn5-cyclopropane-l,2-dicarboxyclic acid (I) was selected 

 as a logical starting point for preparation of acids of this 

 series (20), since it is important to have available models of 

 established stereo-structure for comparison with lactobacillic 

 acid. The monomethyl ester chloride (II) of (I) is con- 

 densed with sodio ethyl acetoacetate, and the resulting 

 crude diketo ester (III) on exposure to sodium methoxide 

 in methanol gives methyl ^rfln5-y-keto-a:,/3-methyleneadipate 

 (IV) (21). Alkylation of (IV) with 77-butyl iodide (V, x = 5) 

 followed by saponification and decarboxylation gives trans- 

 4-keto-2,3-methylenenonanoic acid (VI, x = 5), which is con- 

 verted into <ranj-2,3-methylenenonanoic acid (VII, x = 5) 

 by reduction with hydrazine. Alkylation of (IV) with 

 rz-hexyl iodide (V, x = 1) followed by saponification and 

 reduction affords ^r<2775-2,3-methyleneundecanoic acid (VII, 

 X ^ 1). A superior route to acids of structure (VII) involves 

 condensation of ethyl diazoacetate (VIII) with olefins of the 

 general structure (IX) followed by saponification of the re- 

 sulting esters (X). Starting with octene-1 (IX, x = 5) and 

 decene-1 (IX, x = 7), respectively, 2,3-methylenenonanoic 

 acid (VII, X = b) and 2,3-methyleneundecanoic acid (VII, 

 X = 7) are obtained. Identity of the acids obtained by this 

 route with the corresponding acids prepared from trans- 

 cyclopropane-l,2-dicarboxylic acid (I) establishes their trans 

 configuration. 



For conversion into DL-irfl?75-9,10-methyleneoctadecanoic 

 acid, the acid chloride of (VII, x = 7) is converted into 



