The synthesis of racemic 4-ethyl fatty acids is reported. A Grignard reagent was first prepared by 3-chloroalkane reacting with magnesium and then 4-ethyl fatty acid methyl esters were synthesised by coupling the Grignard reagent with methyl 3-bromopropionate in the presence of the catalyst Li 2CuCl4. The 4-ethyl fatty acid methyl esters were saponified and then acidified to give the 4-ethyl fatty acids. The syntheses of 4-ethylhexanoic acid, 4-ethylheptanoic acid, 4-ethyloctanoic acid, 4-ethylnonaoic acid and 4-ethyl decanoic acid are described. The structures of the 4-ethyl fatty acid methyl esters and 4-ethyl fatty acids were confirmed by 1H NMR, 13C NMR and HRMS.
Unusual Fatty Acids with Specific Odor from Mature Male Goat
Unusual five 4-ethyl-fatty acids were estimated as main constituents of sebaceous gland secretion of male goat which showed the releaser pheromone activity against the estrous female.These acids exist in both free state and ester form.The structures were confirmed by synthesis.Among the five acids, 4-ethyloctanoic acid showed the strong goaty odor at low concentration.