A metathetical cycloaddition-cycloreversion approach to the formation of furan scaffold libraries

A general cycloaddition-cycloreversion metathesis procedure for the selective formation of a furan-based template-directed scaffold is described. In addition, features relative to library construction, such as the chemoselective nature of dipole formation, are discussed. Through the investigation of the temperature sensitive cleavage step, the furan synthesis was found to be accelerated by aqueous medium at physiological temperature leading to pure product from the solid-phase under biologically relevant conditions. The chemoselective nature of the rhodium(II) mediated cycloaddition allowed the selective formation of a key dipole intermediate, in the presence of a number of carbeneactive functional groups, to facilitate the split-pool combinatorial synthesis of a small library of compounds.