Atom Transfer Reactions
Several areas of research are currently being actively pursued, although underlying themes are concerned with the development of new synthetic methodology for natural product and polymer synthesis. Many of these topics are in some way concerned with aspects of organometallic or co-ordination chemistry. For example, we have recently developed a high yielding general method for the reduction of functionalised vinyl stannanes. The products of these reductions undergo facile transmetallation to afford configurationally stable carbanions which have been utilised in the stereoselective synthesis of a variety of terahydrofurans, a motif which is common to a number of natural products. Extension of this methodology has led to the development of a highly stereoselective synthesis of densely functionalised cyclopropanes, which again are representative of a class of compounds present in a range of pharmacologically active compounds (e.g. antifungal agents, pesticides).
Our interest in polymer synthesis has resulted in the identification of a highly efficient catalyst system for Atom Transfer Radical Polymerisation reactions which is currently being exploited by the Polymer Chemistry Section. On the "monomer front" we have also developed a variety of copper catalysts which effect efficient atom transfer cyclisation reaction leading to lactone- and lactam- containing systems which are themselves useful synthetic intermediates. A "tandem" cyclisation reaction (a sequence which is complementary to the Diels - Alder reaction) has also been developed using this chemistry which generates bi-cyclic lactones from acyclic precursors. This chemistry may find application in the synthesis of a number of antitumour agents. During these investigations we have also developed a new concept, that of Catalyst Economy, in which a single catalysts can be utilised in multiple C-C bond-forming reactions.
The chemistry of Group 6 carbene complexes has been extensively utilised in our group over the years, a theme which is continuing in an approach to poly-THF containing acetogenins and aflatoxin β2, whilst palladium chemistry has been utilised in the synthesis of the spiroketal portion of milbemycin β3.
The development of clean reactions is the focus of much research a theme which we have also become interested in. Recent research in our group has shown that high valent metal oxides can efficiently epoxidise olefins in aqueous media using hydrogen peroxide as a re-oxidant. Application of this methodology to carbohydrate chemistry has led to the development of a new method for the synthesis of glycosides, with the possibility that this chemistry could find application to the synthesis of oligosaccharides in a aqueous media. We have also recently discovered a new benzannulation reaction starting from readily available precursors; current efforts are now directed towards synthetic applications in the area of C-glycosides.
Collaboration with the inorganic section is centred on the development of novel ligands for the selective complexation of lanthanides/actinides whilst aldolase mimics based on crown ethers are currently being investigated in collaboration with the physical organic section.