Determination of the absolute configuration of marine oxylipin topsentolide A1 by the synthesis of the enantiomer of the natural product

Two possible stereoisomers of topsentolide A(1), a cytotoxic oxylipin against human solid tumor cell lines, were prepared in order to determine the stereochemistry of natural product. That is, the enantiomer of topsentolide A(1), (85,115,12R)-isomer, and its diastereomer was efficiently synthesized in a stereoselective manner. The stereochemistry of topsentolide A(1) was determined to be 8R,11R,12S by comparing NMR spectra and specific rotations of the synthetic isomers and the natural product. (C) 2010 Elsevier Ltd. All rights reserved.