A divergent synthesis of [1-14C]-mono-E isomers of fatty acids

A convenient synthesis of [1-C-14]-mono-trans fatty acid using olefin inversion as a key-step is described. This methodology allows for a facile synthesis of [1-C-14]-labelled mono-trans analogues of oleic, linoleic and linolenic acids. As an example, only eleven steps were necessary to obtain the [1-C-14]-mono-E isomers of linolenic acid from its commercial all-Z form. In the first step, Barton's decarboxylation procedure yielded a bromo intermediate. Epoxidation of this compound resulted in the formation. of three monoepoxides, which could be separated by HPLC. After identification by H-1 NMR and MS, the pure monoepoxides were then subjected to inversion consisting of a stereospecific deoxygenation followed by a beta-elimination step. Finally, the labelling was introduced by substitution of the bromine by a [C-14]-cyano group followed by hydrolysis. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.