초록
<P>This report describes synthesis of novel structured triacylglycerols (TAGs) and diacylglyceryl ethers (DAGEs) of the 1‐<I>O</I>‐alkyl‐<I>sn</I>‐glycerol type constituting EPA and DHA as the sole fatty acids. One of two TAGs was comprised of a pure EPA located at the 1,3‐positions with pure DHA at the 2‐position and the other had it reversed with a pure DHA at the 1,3‐positions and pure EPA at the 2‐positions. The similarly structured DAGEs were derived from chimyl‐, batyl‐, and selachyl alcohols constituting pure EPA at their <I>sn</I>‐3 position with pure DHA at the <I>sn</I>‐2 position as well as the opposite composition with pure DHA at the <I>sn</I>‐3 position and EPA at the <I>sn</I>‐2 position, the total of six such DAGE products. The syntheses of these compounds were brought about by a two‐step chemoenzymatic process involving a highly regioselective immobilized <I>Candida antarctica</I> lipase to incorporate EPA or DHA activated as acetoxime esters exclusively into the 1,3‐positions of glycerol and the <I>sn</I>‐3 position of the 1‐<I>O</I>‐alkyl‐<I>sn</I>‐glycerols. The second PUFA acyl groups were subsequently introduced to the remaining 2‐positions by EDCI coupling agent to accomplish the title compounds highly efficiently in very high to excellent yields (86–92%).</P><P><B>Practical applications</B>: The work described is based on a previously reported methodology to introduce n‐3 PUFAs activated as oxime esters exclusively into the terminal 1,3‐positions of glycerol and 1‐<I>O</I>‐alkyl‐<I>sn</I>‐glycerols to prepare reversed structured TAGs and DAGEs by use of immobilized <I>Candida antarctica</I> lipase. The methodology is ideal for introducing isotopically labeled fatty acids into predetermined positions of TAGs and DAGEs.</P><P>Novel structured triacylglycerols (TAGs) and diacylglyceryl ethers (DAGEs), constituting EPA and DHA as the sole fatty acids, were obtained by a two‐step chemoenzymatic synthesis comprised of an exclusive incorporation of EPA or DHA, activated as acetoxime esters, into the terminal positions of glycerol and 1‐<I>O</I>‐alkyl‐<I>sn</I>‐glycerols by use of immobilized <I>Candida antarctica</I> lipase, and a subsequent introduction of a second PUFA acyl group to the remaining 2‐positions by EDCI coupling agent.</P>