Effects of polymer architecture and nanoenvironment in acylation reactions employing dendritic (dialkylamino)pyridine catalysts

The role of architecture and nanoenvironment in the catalytic properties of dendritic polymers containing 4-(dialkylamino)pyridines was investigated in the context of acylation reactions employing sterically demanding tertiary alcohols as substrates. Frechet-type benzyl ether and aliphatic ester dendrimers were prepared in a convergent manner from a common trivalent core containing three DMAP groups while a linear polymer was dendronized with aliphatic esters using a divergent growth scheme. Catalysis experiments clearly indicate that nanoenvironment plays the dominant role in determining the activity of the polymer catalysts, with the polyester platform being superior to the benzyl ether. Polymer architecture played little or no role in affecting catalysis. With respect to molecular transport and catalysis, this represents the first comparative study of the effect of architecture and nanoenvironment using structurally similar dendritic materials.