Enantioselective Ribozyme Catalysis of a Bimolecular Cycloaddition Reaction

Ribozyme-catalyzed Diels–Alder reactions: Through the use of either D- or L-ribozymes the absolute configuration of product 3 can be controlled. An ee value of >95 % is reached in the reaction between 1 and 2. The hexaethylene glycol residue attached to 1 and 3 is an atavism that stems from the in vitro selection of the ribozyme. Reactions with substrates not containing this residue are also catalyzed, albeit with lower ee values.