Here is an evidence of the utility of fluorous reagents to pharmacognosists and other chemists dealing with the natural products. In an upcoming article to be published in Tetrahedron Letters (doi:10.1016/j.tetlet.2007.06.077), for the first time, a fluorous tag – catch and release strategy has been designed to the separation of a mixture of three paraconic acids extracted from the Island moss (Cetraria islandica (L.) Ach.).
The (+)-protolichesterinic acid (APL, that always co-elutes with minor AR) was caught and released via a MichaÃ«l / retro-MichaÃ«l addition sequence with a commercially available fluorous thiol, while the resulting two other compounds were classically separated, allowing the isolation of (+)-roccellaric acid (AR) for the first time in this lichen.
This selective chemical extraction not only overcomes the tedious chromatographic process involved to separate these three paraconic acids, but also is efficient giving a three-fold higher yield and a purity of 99%. According to the authors, this methodology may represent an attractive method to facilitate the isolation of minor secondary metabolites and would have potential for automated purification of different natural products in crude extracts, via the use of appropriately functionalized fluorous probes.