A DMAP-functionalized oligocholate foldamer for solvent-responsive catalysis

A hexameric cholate foldamer functionalized with a 4-dialkylaminopyridyl group displayed solvent-sensitive catalysis for the acetylation of alcohols. The catalyst folded in carbon tetrachloride containing a low percentage (<4%) of DMSO and unfolded as more DMSO was added. By increasing the effective concentration of the substrate near the catalytic group, the folded catalyst was more active than the unfolded catalyst toward small, hydrophilic alcohols. The longer and hydrophobic n-octanol, however, was more reactive in the presence of the unfolded catalyst. The highest selectivity (21:1) was observed for methanol/n-octanol with the folded oligocholate catalyst.