Ian Still

Research

Our research group has found new reagents for several synthetic transformations, including the reduction of sulfoxides to sulfides, as well as the reduction of sulfones to sulfoxides, previously unknown in organic synthesis. More recently, we have reported the discovery of an interesting sub-class of sulfines, the a-oxosulfines, which have the unusual property of participating in [4+2] cycloadditions as the diene component and are thus of potential value in the synthesis ofheterocyclic compounds. A procedure which we have recently developed for the controlled regioselective electrophilic thiocyanation of aromatic compounds and subsequent reduction of the thiocyanates, using samarium diiodide, has been shown to provide convenient access to avariety of arylalkyl sulfides and aryl thioesters. Conversion, of ArSCN into ArStBu by a ligand-transfer reaction, using a higher-order cuprate reagent which we have developed, is another important synthetic advance: tBuS has been shown to be a very useful group for directed ortho-metallation procedures.

A second major interest is the synthesis of novel types of naturally occurring compounds, particularly those with demonstrated physiological activity. For example, the syntheses of several indole alkaloids from marine organisms, the euchstomins and eudistomidins, have been achieved. These compounds have been demontrated to possess notable antiviral activity as well as in vivo antitumour activity. Eudistomin L, for example, possesses a tetracyclic structure in which ring D is a 1,3,7-oxathiazepine unit: we effected the first synthesis of the unique structural feature by a completely novel approach. We have also developed an efficient route to the closely related alkaloid (-)-woodinine. Our development of new synthetic methods has led us to the synthesis of the unique and potentially important benzopentathiepin, varacin. Very recently we have completed the synthesis of the marine imidazole alkaloid, xestomauzamine A.