Synthesis of racemic 2,4-dimethyltetradecanoic acid from Mycobacterium kansasii

A known intermediate, (3 R, S; 5 R,S)-3,5-dimethyl-6-triphenylmethyloxyhexanal gave, in a Wittig reaction with 1-octyltriphenylphosphonium bromide and n-butyl lithium in anhydrous tetrahydrofuran, a mixture of olefininic compounds. Trityl deprotection and hydrogenation of the double bond afforded the (2 R, S; 4 R,S)-2,4-dimethyltetradecanols. Oxidation of the alcohol functionality using pyridinium dichromate in anhydrous N,N'-dimethylformamide gave racemic, (2 R, S; 4 R,S)-2,4-dimethyltetradecanoic acids, which were converted to their methyl esters. 2,4-Dimethyltetradecanoic acids are constituents of glycolipid antigens from Mycobacterium kansasii.