Passive Template Effects and Active Acid‐Base Involvement in Catalysis of Organic Reactions

A series of receptors were prepared all containing two adenine binding sites linked by various spacers. Their ability to act as templates in the coupling of two adenine derivatives, an active ester and an amine, in CHCl 3 was evaluated. The accelerations varied from none to 700‐fold. Binding studies of the coupling product with these templates confirmed involvement of both binding sites. When the spacer was a 1,10‐phenanthroline unit, an efficient hydrolysis reaction of the active ester was observed. Another series of receptors were prepared containing one adenine receptor and various polar functional groups. The molecules were evaluated as catalysts in the coupling of an adenine‐derived active ester and n ‐butyl‐amine. The orientation as well as the nature of the functional group greatly influenced the coupling rate. A carboxylate group was most effective, accelerating the intracomplex reaction 250‐fold.