SYNTHESIS OF A DERIVATIVE OF RACEMIC 3-HYDROXY-2,4,6-TRIMETHYLTETRACOSANOIC (MYCOLIPANOLIC) ACID AND RACEMIC 2,4,6-TRIMETHYLTETRACOS-2-ENOIC (MYCOLIPENIC) ACID

Racemic 2,4-dimethyldocosanol, available from previous studies, was ox idised to the aldehyde using pyridinium chlorochromate. Aldol reaction of 2,4-dimethyldocosanal with methyl propionate afforded racemic meth yl 3-hydroxy-2,4,6-trimethyltetracosanoic acid. The hydroxy function w as protected as a tert-butyldimethylsilyl ether and the ester function ality hydrolysed to the free acid. Wittig reaction of 2,4-dimethyldoco sanal using 1-carboethoxyethylidenetriphenylphosphorane afforded the ( E)-stereoisomer following removal of the small quantities of (Z)-isome r by column chromatography. The ethyl ester was hydrolysed to afford r acemic 2,4,6-trimethyltetracos-2-enoic acid. These unusual fatty acids are characteristic of Mycobacterium tuberculosis.