Tritioboration and synthesis of tritium-labeled polyunsaturated fatty acids

Methyl esters of polyunsaturated fatty acids labeled with tritium were prepared by partial stereoselective reduction of the corresponding acetylenic esters with tritiated disiamylborane, followed by protonolysis with tritiated acetic acid. The labeling was strictly specific, and the tritium atoms were located only at the carbon atoms forming the unsaturated bond(s). Synthesis of some tritiated fatty acid methyl esters with methylene-interrupted trans-cis double bonds is also reported.