Preparation of cis,cis-, trans,cis-, cis,trans- and trans,trans-12,15-octadecadienoic-9,10-d2 acids, methyl esters and triglycerides

Methyl cis,cis-, trans,cis-, cis,trans-, and trans,trans-12,15-octadecadienoates-9,10-d2 were prepared by the Wittig Reaction between cis- or trans-3-hexenyltriphenylphosphonium bromide and methyl 12-oxododecanoate-9,10-d2 with butyl lithium in ethyl ether. At room temperature, the Wittig Reaction gave a product mixture with 80-85% cis geometry in the double bond formed. When the reaction was run at −40°C, followed by protonation with methanol and slow warm-up to room temperature, the product mixture had 60-65% trans geometry in the double bond generated. Mixtures of the cis,cis and trans,cis and of the cis,trans and trans,trans isomers were separated by partial silver resin chromatography, and the individual pure fatty esters were converted to the triglycerides through the respective acid chlorides. Melting points and nuclear magnetic resonance chemical shifts are presented.