Ozone fatty acid oxidative cleavage

By this method (Z)-monounsaturated fatty acids and esters could be obtained with an ( )-isomer content of less than 10% this stereoselectivity being however inferior to that of the commonly used acetylenic approach 55,56). However, the salt-free techniques used today in Wittig reactions allow (Z)-alkenoic acids to be synthesized with less than 2% of the ( )-isomers. Thus, Bestmann et al. prepared methyl and ethyl esters of (Z)-4,5,6,7,8,9,ll- and 13-alkenoic acids of different chain lengths 35,57 62), which served as intermediates in the synthesis of insect pheromones, both by reaction of co-alkoxycarbonyl-substituted alkyl-triphenyl-phosphonium salts with simple alkanals and of co-formylalkanoic esters with alkylidenephosphoranes. As the starting material for the synthesis of -substituted alkyl-phosphonium salts co-chloro- and -bromocarboxylic esters were used. The corresponding -substituted aldehydes can usually be obtained by ozone cleavage of suitable olefin derivatives or by oxidation of alkohols 57,58). 

Beside the two-step oxidative cleavage unsaturated fatty acids - ketofatty acids -> dicarboxylic acids, we also studied direct oxidative cleavage of C = C-bonds without ozone. Such an alternative to ozonolysis is given by the ruthenium catalysed oxidative C = C-cleavage. This synthesis is based on work of C. Djerassi... 

Oxidative cleavage of the double bond in tall oil derived fatty acid may be carried out with ozone pelargonic and azelaic acids are the major acids formed (36). 

Warwel, S., and M. Riisch gen. Klaas, Oxidative Cleavage of Urrsatiuated Fatty Acids Without Ozone, Lipiii. Technol. 79 10-14(1997). 

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