46872-AC1
A Metal-Mediated Approach to Ring Construction
Progress in the last funding cycle has been made on numerous fronts. A number of platinum complexes bearing N-heterocyclic carbenes (NHC) were synthesized and fully characterized. These complexes are presently being tested in catalytic ring-forming reactions. The NHC-gold (I) systems we previously reported have now been examined in reactions involving propargylic esters and here we have found some very exciting reactivity and the formation of unusual ring systems as a function of the catalyst and ligand borne on the gold metal center. This specific contribution, investigating the reaction products and mechanistic aspects of this chemistry, was selected as the cover art of the Angew. Chem. issue in which it appeared. The cyclization chemistry was also described in an Accounts publication highlighting the very unusual nature of the gold chemistry bearing NHC ligands. Related copper-NHC complexes have been found very efficient in performing hydrosilylation reactions. Finally, in order to better understand ligand effects in NHC modified systems, we have reported on the thermodynamics associated with NHC dimerization and the driving forces behind such behavior as a function of substitution pattern on the NHC.
