Toward new biosilicones: hydrosilylation of fish oil unsaturated fatty acid esters

Hydrosilylation of fatty acid methyl esters (FAMEs) were efficiently cataly zed by Speier's and Wilkinson's catalysts in the case of vinylic acid ester s, but less efficiently in the case of non-vinylic ones, which gave non-reg iospecific additions, In the latter case, initiation by radicals led to reg iospecific reactions for oleic esters (C10-silylation). This regiospecifici ty can be attributed to the higher stability of the C10-silylated adduct an d of the corresponding radical intermediate. Only regioselective addition w as observed for linoleic esters (C13-silylation approximate to 70%, C10 app roximate to 20%, C9 x 10%). Molecular modeling was used to examine the stab ility of the isomeric products and radicals. The new concept of radical ini tiation sequence has been successfully applied to FAMEs and then was extend ed to crude fish oil. Copyright (C), 2001 John Wiley & Sons, Ltd.