A molecule that can catalyze its own formation can also exploit reactions in a dynamic combinatorial library to amplify its formation at the expense of other species, Scottish researchers report (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200804223). Douglas Philp and Jan W. Sadownik at the University of St. Andrews started with a pool of four reagents that react to form unreactive imines and reactive nitrones. The nitrones undergo irreversible dipolar cycloaddition reactions with a maleimide to form two pairs of diastereomeric cycloadducts, one of which can catalyze its own formation. This autocatalyzing replicator becomes the predominant product. Adding a small amount of the replicator as a template to the reagent pool causes it to become the predominant species even faster. "Chemical synthesis to date has focused on the creation of single chemical entities from carefully controlled reaction mixtures," Philp says. "We are trying to turn this around by having a general-purpose reagent pool that can be reconfigured as required. We see the application of this technology in nanoscale fabrication."