Chiral homoallylic and allylic sulfoxides as models for the stereochemical analysis of sulfoxide thiaoleates

摘要

Both enantiomers of n-butyl allyl sulfoxide have been synthesized and are reported as models of bio-oxidized thiafatty acid analogues. The stereochemical analysis of these aliphatic sulfoxides as well as their homoallylic counterparts, were performed by the use of chiral NMR shift reagents. We first checked the validity of the chiral solvating NMR reagents method using the alpha-methoxyphenylacetic acid (MPA) and the Pirkle-like alcohol 1-(9-anthryl)-2,2,2,-trifluoroethanol (TAE). We then compared the relative efficiency of these reagents in the enantiomeric discrimination of our sulfoxide models and determination of their enantiomeric excess. On the basis of experiments conducted on our real targets, optically enriched sulfoxides from the Chlorella incubations of 12- and 13-thiastearic acids, the versatality of these NMR reagents for the ee determination as well as the assignment of the absolute configuration at sulfur, are discussed. (C) 2004 Elsevier Ltd. All rights reserved. [References: 31]